Aiming at the root mean square error (RMSE) of positioning and the poor ability of positioning deviation to adapt to the measurement noise of the current time-difference/frequency-difference passive positioning algorithms, a kind of improved constraint-weighted least squares method based on Lagrange multipliers is proposed The positioning performances of the proposed method and two-stage weighted least squares (TSWLS) are compared by computer simulation under near and far field conditions, respectively. The simulation experiments show that the proposed algorithm has good positioning effect for both near-field and far-field targets, and can meet the high accuracy and real-time positioning under certain noise interference conditions.