Abstract: The problem of eliminating location ambiguity in passive time difference of arrival(TDOA) systems is considered. The accuracy analysis and the simulation results of four-variable algorithm show that its performance is poor regardless of the capability of eliminating location ambiguity. Based on the traditional TDOA location algorithm, a subset fusion algorithm of multiple subsystems was presented. The proposed algorithm can fully utilize the redundant information come from passive sensors, so it not only can eliminate location ambiguity, but also improve the location accuracy. In comparison with the four-variable algorithm, subset fusion algorithm of multiple subsystems is superior to the alternative algorithm in terms of location accuracy. The simulation results prove that the new algorithm is effective and practicable.