Aiming at the problem of lacking in design automation and generalization during the process of instrument selection and resource configuration of automatic test system(ATS), a kind of matching function was presented to describe the matching degree between test point and instrument port. Matching function was built with signal-oriented method, and it integrated signal properties of test point, capability parameters of instrument, and instrument- s price, reliability, operation complexity and so on. The strategy and algorithm for matching test point and instrument port were proposed. And the strategy was also optimized to meet the requirement of parallel test. The method was validated by an example and the result showed that it could reduce test cost, enhance system reliability and improve test efficiency and throughput.