The directional accuracy and wavelength resolution is highly dependent on the laser spot center location accuracy for the super wide-angle laser warning system based on grating diffraction. The spot features of this system was analyzed. As the imaged spots became tilt and its intensity was similar to Gaussian distribution with the laser arrival angle increasing, a new improved Gaussian fitting algorithm was proposed to locate the spot center. Then the accuracy and stability were verified by simulation and experiment test. The simulation results show that when the angle between long axis of imaged spot and x axis increases from 0° to 80° with standard error of Gaussian noise 0.01, mean errors and standard error of this method are smaller than 0.005 pixel and 0.02 pixel, respectively. The experiment test shows that after pre-process of frame subtraction and Gaussian filtering, results of the proposed method are close to weighted centroid and Gaussian fitting if the long axis of imaged spot is parallel to x or y axis, and both mean error and standard error for laser incoming direction of this proposed method are smaller than the other two methods when the imaged spot is tilted.