In order to obtain the relative position information of thunder source generated by lightning, a three-dimensional cross array composed of seven microphones is established by using spatial geometric azimuth estimation algorithm. On this account, a lightning localization method is proposed to realize array-based omnidirectional lightning detection. Firstly, according to the distances from the thunder source to each microphone, the coordinate calculation formula of the thunder source is deduced. Among them, a pair of microphones along the Z axis are adopted to determine the positive and negative of the parameters in the Z direction of the coordinate. Then, based on the theory of indirect measurement error, the relationship between element spacing, angle and distance of thunder source and localization accuracy is studied and analyzed. Simulation results show that the coordinate error rate of thunder source measured by this method is about 0.01%, and the angle error rate is about 0.005%. This not only achieves good localization effects, but also effectively solves the problems of large amount of calculation and low accuracy of the existing works.