This paper proposes a high-precision passive geolocation method aiming at ground targets.This method uses a rotating ellipsoid model parallel to the surface of the earth and the posture angles of the line-of-sight of the photoelectric detector system to deduce the analytical algorithm of the high-precision passive geolocation of ground targets.In order to improve the precision of measurement and positioning,based on the motion of ground targets in the earth coordinate system,a current statistical model of the acceleration is established and taken as the state equation,the solution of passive geolocation of ground targets is taken as the measurement equation,and the method of standard Kalman filtering is used to further improve the target-positioning accuracy.The method calculates the effects of the earth′s curvature and avoids the secondary multiplication of the errors.This algorithm is simple with high precision.Compared with that of the traditional geolocation method,which conducts positioning calculation based on the exact value of laser ranging after estimating the relative distance of the target first,the positioning accuracy of the proposed method is promoted greatly.