Abstract: For problems of difficult determination and big error of mine microseism source depth, a determination method of microseism source depth was proposed by only using travel time of P wave. Firstly, plane coordinates and start time of microseism source are calculated through an improved linear location method. Secondly, based on epicentral distance and travel time of microseism between microseism source and station, TD mode fitting is conducted firstly and DT mode fitting is conducted after eliminating error data. Finally, microseism source depth is determined according to intercept of fitting straight line. The actual application results show that the method can effectively reduce interference of error measured data and improve measuring accuracy of microseism source depth.