Abstract: This paper employs an Input-Orientated Data Envelopment Analysis approach to th e efficiency-based evaluation of the performance of Chinese stock commercial ba nks before the entry into WTO. First, we choose ten nationwide stock commercial banks in 2001 as samples, define deposit as input and output respectively, and c alculate the technical efficiency of banks as index to evaluate their performanc e. Then, we decompose the technical efficiency into pure technical efficiency an d scale efficiency, and set the return scale to banks. At the same time, we rank the banks in the sequence of technical efficiency, differentiating the banks wi th best performance from those with relatively poor performance, and analyze the origin of their poor performance. Finally, we discuss the differences with the performance of banks caused by different definitions of deposit and accordingly give a reasonable account.