Several typical styles of helicopters encircled sonobuoy arrays are introducedand the sonobuoys position models are establishedwhich provides a scientific theoretical basis for sonobuoy placing.The distribution model of submarines initial position was set up and the method for calculating the distribution radius of the submarines was described.Thenthe submarines maximum velocity was estimated mathematically based on some specific hypothesises.The submarines maximum velocity was defined as twice of its economical speedwhich rationality was demonstrated through the probability theory.In this waythe submarines velocity obeys Rayleigh Distribution.Finallysimulation was made about the effect of the submarines initial position distribution and their economical speed on the antisubmarine searching probability of the encircled sonobuoy arraysand some results were obtained.