Abstract: To ensure laser proximity fuze of anti-torpedo torpedo (ATT) detecting the torpedo target in rendezvous process, the minimum scanning frequency and the minimum pulse frequency that can satisfy requirement was calculated. The working principle of laser proximity fuze was studied, and the critical condition of the minimum scanning frequency and pulse frequency that make the fuze just detect the target were obtained. The rendezvous relations between ATT and target were described by three kinds of coordinate system, the computation models for the minimum scanning frequency and pulse frequency were built, and the changing rules of the minimum scanning frequency and pulse frequency were got. Through simulation test to prove the correctness of the built computation models, the test results tally was in line with the theoretical results. The minimum scanning frequency and pulse frequency that is necessary to intercept different typical torpedoes were calculated. Thus, this work can provide a theoretical basis for designing the scanning frequency and pulse frequency of laser proximity fuze.