The positioning accuracy of star points is essential in astronomical navigation, which affects the accuracy of astronomical navigation. The traditional method for improving the resolution of a star map based on linear interpolation directly uses the linear relationship to calculate the gray value of insertion, however it ignores the own change characteristics of original functions. In view of the imaging characteristics of star points, a method of star location is proposed based on improved linear interpolation. First, we establish the imaging model of star points, deduce the one-dimensional model, and obtain the concave convex boundary point by calculating the second-order derivative. Then we give the method for calculating the weighting factor of improved linear interpolation, and finally the location of star points is realized. The simulation results show that, compared with the traditional method, the proposed method has an average deviation error reduced by 15.4%, and it can effectively extract the center of star points.