下表列出了所有的Lua語言支持的關係運算符。假設變量A持有10和變量B持有20則：

運算符	描述	示例
==	檢查兩個操作數的值是否相等，如果是則條件變為真。	(A == B) 不為 true.
~=	檢查兩個操作數的值是否相等，如果值不相等，則條件變為真。	(A ~= B) 為 true.
>	檢查左操作數的值是否大於右操作數的值，如果是，則條件成立。	(A > B) 不為 true.
<	檢查左操作數的值是否小於右操作數的值，如果是，則條件成立。	(A < B)  為  true.
>=	檢查左操作數的值是否大於或等於右操作數的值，如果是，則條件成立。	(A >= B) 不為 true.
<=	檢查左操作數的值是否小於或等於右操作數的值，如果是，則條件成立。	(A <= B)  為  true.

示例

試試下麵的例子就明白了所有的Lua編程語言提供的關係運算符：

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

當建立並執行上麵的程序它會產生以下結果：

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