The problem that passive location to a fixed emitter with an airborne single observer applied in air-to-ground anti-radiation missile (ARM) was discussed. The measurement information of the azimuth and its change rate was introduced, the status model and the measurement model were established, the EKF algorithm was applied, and the location and track of the radar target were realized. Monte Carlo simulation shows that if the distance between the observer and the radar changes within a certain scale, the curve of the relative error of its distance varies to convergence at a small value in the wake of the times of observation increasing. It illuminates that the location and the track of the target acquired by the airborne observer reaches a superior precision.