In this paper, we conduct research on Standard Interchange Protocol 2 (SIP2). Then, based on the research, a SIP2 class is designed using object-oriented model. The SIP2 class includes several methods, which comprise check in, check out, patron status, and so forth. To demonstrate its functionality, we use the SIP2 class in a new library circulation system. Compared to traditional protocols for transaction in library system, test results show that our implementation of SIP2 class works well and has a better performance.