Abstract: In order to solve the problem that the uncertain information is difficult to quantitative analysis in the process of software maintenance,this paper uses the comentropy to quantitative measure the risk in software maintenance.A quantitative analysis algorithm about the comentropy is proposed,and the software risk maintenance model is put forward based on the comentropy,in addition,this paper uses the comentropy algorithm quantitative calculate the uncertain degree and loss degree in the process of software maintenance.The emulational result demonstrates that based on the software risk maintenance model,using the comentropy algorithm is able to quantitative measure the risk in software maintenance.