Aimed at the problem that the UAV′s(unmanned aerial vehicle′s) single station angle and distance measurement are greatly affected by the UAV′s attitude angle error, a method was proposed to solve the UAV′s attitude by detecting the auxiliary beacon and combining with the inertial sensor. The attitude solving model of inertial sensor based on cubature Kalman filter was established. By using the gradient descent method, the attitude parameters of UAV based on auxiliary beacons were solved, and the results were comprehensively used to estimate and correct the attitude error of UAV. Finally the targets′ location and simulation calculation under different fields of view were completed. The results show that the proposed method can improve the precision of UAV target location.