In order to improve the sufficiency of software test, the concept of exception test case is put forward and analyzed by examples firstly in this paper, Secondly, since the obtaining method of exception test cases differs greatly to traditional security test cases, a distributed-storage method is proposed to store and share exception test cases on a P2P network. To realize sharing and reusing of exception test cases, a set of methods to improve the test case library algorithm of the local network are proposed.