Abstract: A joint passive localization and bias registration algorithm using Direction of Arrival (DOA) and Time Differences of Arrival (TDOA) measurements is proposed to solve the localization problem in the multi-static passive radar system using illuminators of opportunity under the influence of system error. Firstly, the nonlinear DOA and TDOA measurement equations are linearized by introducing an intermediate variable. Then, a joint estimation of target location and system biases are obtained by a recursive weighted least squares algorithm. Moreover, a dependent least squares algorithm is developed to improve the initial estimation using the relationship between the intermediate variable and target location variables. Finally, an iterative post-estimate procedure is exploited to further enhance the accuracy of target localization. Simulations indicate that the proposed algorithm can effectively estimate the system biases and target state.