Abstract: To improve acquisition rate of laser proximity fuze in ATT(anti-torpedo torpedo) in detecting the torpedo target, the changing rules of target echo power with laser beam incident angle and position were analyzed according to torpedo targets laser reflection characteristics. The rendezvous model of ATT and attacking torpedo was described by using spatial analytic geometry method. And the target echo power calculation method at any intersection distance and attitude was given. The Monte Carlo simulation model of acquisition rate in underwater single beam scanning laser fuze was established based on system minimum detecting power, and the system acquisition rate changing with laser pulse frequency was calculated. The maximum acquisition rate and corresponding laser scanning frequency and pulse frequency were obtained when the target was at different distance. The results showed that the system can reliably acquire the target at a distance of 9 m, when the laser scanning frequency is 15 Hz, and the pulse frequency is 4 kHz. Thus, this work can provide a theoretical basis for designing the single beam scanning laser fuze of ATT.