下表列出了所有的Lua语言支持的关系运算符。假设变量A持有10和变量B持有20则：

运算符	描述	示例
==	检查两个操作数的值是否相等，如果是则条件变为真。	(A == B) 不为 true.
~=	检查两个操作数的值是否相等，如果值不相等，则条件变为真。	(A ~= B) 为 true.
>	检查左操作数的值是否大于右操作数的值，如果是，则条件成立。	(A > B) 不为 true.
<	检查左操作数的值是否小于右操作数的值，如果是，则条件成立。	(A < B)  为  true.
>=	检查左操作数的值是否大于或等于右操作数的值，如果是，则条件成立。	(A >= B) 不为 true.
<=	检查左操作数的值是否小于或等于右操作数的值，如果是，则条件成立。	(A <= B)  为  true.

示例

试试下面的例子就明白了所有的Lua编程语言提供的关系运算符：

a = 21
b = 10

if( a == b )
then
   print("Line 1 - a is equal to b" )
else
   print("Line 1 - a is not equal to b" )
end

if( a ~= b )
then
   print("Line 2 - a is not equal to b" )
else
   print("Line 2 - a is equal to b" )
end

if ( a < b )
then
   print("Line 3 - a is less than b" )
else
   print("Line 3 - a is not less than b" )
end

if ( a > b ) 
then
   print("Line 4 - a is greater than b" )
else
   print("Line 5 - a is not greater than b" )
end

-- Lets change value of a and b
a = 5
b = 20
if ( a <= b ) 
then
   print("Line 5 - a is either less than or equal to  b" )
end

if ( b >= a ) 
then
   print("Line 6 - b is either greater than  or equal to b" )
end

当建立并执行上面的程序它会产生以下结果：

Line 1 - a is not equal to b
Line 2 - a is not equal to b
Line 3 - a is not less than b
Line 4 - a is greater than b
Line 5 - a is either less than or equal to  b
Line 6 - b is either greater than  or equal to b