In order to improve the detection accuracy of the four-quadrant detector for laser spot center location and simplify the existing algorithm,the two-section polynomial fitting method was proposed.When the spot energy distribution is Gaussian distribution model,the processing of data can be simplified according to the symmetry of the four-quadrant detector.And then the fitting range was divided into two sections for polynomial fitting.Meanwhile,the algorithm was optimized because the fitting error is bigger on the sides of the fitting range.The simulation results show that when the highest degree of polynomial is four,the fitting error is only 10-5mm orders of magnitude in the range near the origin and 10-4mm orders of magnitude in the range away from the origin.At last,the experiment proves the feasibility of the proposed algorithm.