Passive location systems are susceptible to the Earths curvature when detecting long-range targets,and the process of unifying the coordinate systems of multiple observation stations introduces additional errors into the system,resulting in large deviations between the target position estimated by the system and the real target position,which in turn causes serious consequences on the subsequent data correlation and information fusion.In view of this,this paper proposes a passive location algorithm using Time Difference of Arrival (TDOA),which is based on two-station coordination considering the Earths curvature.Firstly,all geographical coordinates are converted to geodetic Cartesian coordinate system.Then,the information of TDOA of the target is received by the two stations.Finally,the geodetic Cartesian coordinates of the target position are solved based on the elliptic equation of the Earth and the method of Taylor series expansion.Theoretical analysis and simulation experiments show that the proposed algorithm can overcome the influence of the Earths curvature,realize the standardization of the coordinate systems of the location system,and effectively reduce the location error,which provides a new technical idea for the passive detection of long-range targets.