Message-digest algorithm is widely applied in the field of e-commerce and information security，and its unidirectionality and collision resistance are the keys to the algorithm. By using splitting and summing of integer vector，combining with the irreversibility of data interception and extensibility of nonlinear transform matrix, a new message-digest algorithm is constructed. The algorithm is described，discussed and verified through designed test cases. Test results show that the algorithm can achieve the desired effect. with the advantages of being concise，flexible，logical and widely applicable.