For the precise location of laser spot center on the complex target, a method based on residual pruning with geometric feature constraints is proposed. Firstly, the laser spot is extracted by analyzing the character of imaging. Then, the edge of laser spot is pruned twice with the geometric feature constraints to optimize the edge. Finally, the location of laser spot center is acquired accurately by using the least square fitting method. And it’s applied to the curvature measurement, an important status parameter of cannon. Experimental results show that the method proposed is quite stable, fast and accurate. Compared with the traditional location methods, the horizontal and vertical location errors of laser spot on the complex target are both improved from±1.2 pixel to±0.2 pixel. And the time of a signal location is less than 0.31s. It can accomplish the location of laser spot center on the complex target with high speed and accuracy.