1. 忽略转义字符

例如

string fileName = "D:\\文本文件\\text.txt";

使用@后

string fileName = @"D:\文本文件\text.txt";

2. 让字符串跨行

例如

string strSQL = "SELECT * FROM HumanResources.Employee AS e"
   + " INNER JOIN Person.Contact AS c"
   + " ON e.ContactID = c.ContactID"
   + " ORDER BY c.LastName";

使用@后

string strSQL = @"SELECT * FROM HumanResources.Employee AS e
    INNER JOIN Person.Contact AS c
    ON e.ContactID = c.ContactID
    ORDER BY c.LastName";

3. 在标识符中的用法

C#是不允许关键字作为标识符(类名、变量名、方法名、表空间名等)使用的，但如果加上@之后就可以了，例如

public static void @static(int @int) {
    if (@int > 0) {
        System.Console.WriteLine("Positive Integer");
    } else if (@int == 0) {
        System.Console.WriteLine("Zero");
    } else {
        System.Console.WriteLine("Negative Integer");
    }
}