Abstract: The detection performance of multistatic sonar systems is analyzed.At first,with the likelihood ratio test,the optimum receivers of active multistatic sonar systems are deduced from a Gaussian random process in the presence of additive white Gaussian noise.The optimum receiver of active multistatic sonar systems is a matched filter.Then a simplified receiver based on the sum detector is put forward and its performance is analyzed.It can be seen that when the detection performance of any static is much better than other statics,the detection performance of the sonar system will not be improved or even degrade when adding more statics to the system.On the other hand,when the signal to noise ratio of the input of each static is in a close range,the detection performance of the sonar system will be improved as adding more statics.