Based on the beam have been designed by the code for design of concrete structures in China, the value of some parameters were converted into the corresponding value which are from the code in America and Europe by the conversion formula, and then the calculation and control of the maximum crack width of reinforced concrete structure come from these three code were compared and analyzed . The results show that the value of the maximum crack width obtained from the code in China is larger than American and European, but under the similar work environment, the control of the maximum crack width with the code in China is relatively stricter.