出处：RegExLib.com Regular Expression Cheat Sheet (.NET)

元字符 说明 字符转义 说明 字符类 说明

^	匹配字符串的开始位置
$	匹配字符串的结束位置
.	匹配任意单个字符（换行符 n 除外）
|	交替
{…}	指定要限定的数量
[...]	指定要匹配的字符集
(…)	对表达式进行逻辑分组
*	匹配零或多个前面的表达式
+	匹配一或多个前面的表达式
?	匹配零或一个前面的表达式
	放在上面任何一个字符之前，表示匹配该字符本身。放在其他特殊字符后面，表示字符转义（见下面）
原始字符	除 . $ ^ { [ ( | ) ] } * + ? 之外的字符均匹配自身
a	匹配铃声（闹铃）u0007
b	在[]中匹配一个空格 u0008，在其他情况下匹配字边界（位于 w 和 W 字符之间）
t	匹配制表符 u0009
r	匹制回车符 u000D
v	匹配垂直制表符 u000B
f	匹配换页符 u000C
n	匹配换行符 u000A
e	匹配退出键（符） u001B
40	匹配以八进制表示的 ASCII 字符（最多三位数）；在没有前导零的情况下，如果只有一位数字或者相应数字与某个捕获组的编号对应，那就是反向引用（backreference）。字符 40 表示一个空格。
x20	匹配以十六进制表示的 ASCII 字符（两位数）
cC	匹配 ASCII 控制符，例如 cC 匹配 Ctrl+C
u0020	匹配以十六进制表示的 Unicode 字符
*	反斜杠后面如果不是一个可转义的字符，则匹配该字符本身。例如，* 就相当于x2A
.	匹配除 n 之外的任意字符。
[aeiou]	匹配特定字符集中包含的任意一个字符
[^aeiou]	匹配特定字符集中不包含的任意一个字符
[0-9a-fA-F]	连字符（-）用来指定连续的字符范围
p{name}	匹配由{name}指定的命名字符类中的任意字符
P{name}	匹配不包含在{name}指定的组或块范围中的文本
w	匹配英文数字字母字符，在指定兼容ECMAScript的情况下，等价于[a-zA-Z0-9]
W	匹配非英文数字字母字符，在指定兼容ECMAScript的情况下，等价于[^a-zA-Z0-9]
s	匹配任意空白字符，在指定兼容ECMAScript的情况下，等价于[fnrtv]
S	匹配任意非空白字符，在指定兼容ECMAScript的情况下，等价于[^fnrtv]
d	匹配数字字符，在指定兼容ECMAScript的情况下，等价于[0-9]
D	匹配非数字字符，在指定兼容ECMAScript的情况下，等价于[^0-9]

英文版:

Metacharacters Defined MChar Definition

^	Start of a string.
$	End of a string.
.	Any character (except n newline)
|	Alternation.
{...}	Explicit quantifier notation.
[...]	Explicit set of characters to match.
(...)	Logical grouping of part of an expression.
*	0 or more of previous expression.
+	1 or more of previous expression.
?	0 or 1 of previous expression; also forces minimal matching when an expression might match several strings within a search string.
	Preceding one of the above, it makes it a literal instead of a special character. Preceding a special matching character, see below.

Metacharacter Examples Pattern Sample Matches

^abc	abc, abcdefg, abc123, ...
abc$	abc, endsinabc, 123abc, ...
a.c	abc, aac, acc, adc, aec, ...
bill|ted	ted, bill
ab{2}c	abbc
a[bB]c	abc, aBc
(abc){2}	abcabc
ab*c	ac, abc, abbc, abbbc, ...
ab+c	abc, abbc, abbbc, ...
ab?c	ac, abc
asc	a c

Character Escapes http://tinyurl.com/5wm3wl Escaped Char Description

ordinary characters	Characters other than . $ ^ { [ ( | ) ] } * + ? match themselves.
a	Matches a bell (alarm) u0007.
b	Matches a backspace u0008 if in a []; otherwise matches a word boundary (between w and W characters).
t	Matches a tab u0009.
r	Matches a carriage return u000D.
v	Matches a vertical tab u000B.
f	Matches a form feed u000C.
n	Matches a new line u000A.
e	Matches an escape u001B.
40	Matches an ASCII character as octal (up to three digits); numbers with no leading zero are backreferences if they have only one digit or if they correspond to a capturing group number. (For more information, see Backreferences.) For example, the character 40 represents a space.
x20	Matches an ASCII character using hexadecimal representation (exactly two digits).
cC	Matches an ASCII control character; for example cC is control-C.
u0020	Matches a Unicode character using a hexadecimal representation (exactly four digits).
*	When followed by a character that is not recognized as an escaped character, matches that character. For example, * is the same as x2A.

Character Classes http://tinyurl.com/5ck4ll Char Class Description

.	Matches any character except n. If modified by the Singleline option, a period character matches any character. For more information, see Regular Expression Options.
[aeiou]	Matches any single character included in the specified set of characters.
[^aeiou]	Matches any single character not in the specified set of characters.
[0-9a-fA-F]	Use of a hyphen (–) allows specification of contiguous character ranges.
p{name}	Matches any character in the named character class specified by {name}. Supported names are Unicode groups and block ranges. For example, Ll, Nd, Z, IsGreek, IsBoxDrawing.
P{name}	Matches text not included in groups and block ranges specified in {name}.
w	Matches any word character. Equivalent to the Unicode character categories [p{Ll}p{Lu}p{Lt}p{Lo}p{Nd}p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, w is equivalent to [a-zA-Z_0-9].
W	Matches any nonword character. Equivalent to the Unicode categories [^p{Ll}p{Lu}p{Lt}p{Lo}p{Nd}p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, W is equivalent to [^a-zA-Z_0-9].
s	Matches any white-space character. Equivalent to the Unicode character categories [fnrtvx85p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, s is equivalent to [ fnrtv].
S	Matches any non-white-space character. Equivalent to the Unicode character categories [^fnrtvx85p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, S is equivalent to [^ fnrtv].
d	Matches any decimal digit. Equivalent to p{Nd} for Unicode and [0-9] for non-Unicode, ECMAScript behavior.
D	Matches any nondigit. Equivalent to P{Nd} for Unicode and [^0-9] for non-Unicode, ECMAScript behavior.