In order to solve the problem of the test pattern optimal generation in boundary-scan test, a new algorithm, called test matrix compress algorithm, is presented. In the new algorithm, firstly, set up the limited-short-fault-Model applying the structural information of the circuit board on test; then, based on the limited-short-fault-Model, carry out compressing process on the complete test matrix to generate optimal test matrix. The main idea of this algorithm is to remove invalid or redundant information from test matrix to the greatest extent, while keeping the effective test information. Through theoretic analysis and experimental validation, it is proved that the algorithm can get good optimization result and achieve great test information compressing ratio by this algorithm.