Aimed at the practical problem that the accuracy of air airborne single station passive location is limited by the error of parameter measurement, this paper presents a grid search passive location method to improve the error of phase difference. Firstly, the phase difference information is filtered out by LMS adaptive filtering, and then the positioning equation is established by using the observed phase difference according to the positioning model. Finally, the location of the radiation source target is solved by the grid search method. The target of radiation source can be located at by the method accurately under the condition of large phase difference measurement error. The simulation results show that the phase difference error filtered can be reduced to less than 0.14rad,and the positioning result is better than that of reference［17］. The positioning error is shown that within 10 degrees at the phase error, increasing the mesh resolution and extending the observation time can improve the positioning accuracy, and can verify further the necessity to obtain the accuracy, and to obtain the accurate phase difference information simultaneously.