In the cloud computing environment, the execution environment of network security protocols becomes more complex than ever before. The use of Web security issues open license agreement can improve the security of information sharing. CPN (Colored Petri Net) is employed to model OAuth protocol. The analysis of authorization code pattern in OAuth protocol adopts simulation tool named CPNTools. The experimental results show that the authorization code pattern can be verified and authorized based on token. Authorization token injection attack can be prevented in this way.