An algorithm for target localization based on Doppler frequency and azimuth measurement in passive detection system is proposed. The mathematical model and the computational relationship are constructed for passive detection system. Also the computation progress for target localization and the process for fuzzy solution are given. In the simulation experiment, a typical scene is constructed by using the STK modeling tool, and the precision of target localization is also analyzed. Finally, the conclusion is given that the algorithm for target localization based on Doppler frequency and azimuth measurement is effective.