Abstract: Because of the area distortion of Gauss projection, it is necessary to calculate the map patch area on Earth ellipsoid with high area precision in some applications.In this paper, the area calculation method of ellipsoid patch is studied and improved, and the improved algorithm is analyzed empirically. The results show that the approximating definite integrals by the improved Rectangular Rule has higher computational efficiency than by the conventional rectangular rule. The improved rectangle method can replace the middle layer algorithm and the bottom algorithm in ellipsoid patch area calculation method and simplify the calculating process. With the help of decimal number type variables in C # language, a high accuracy value of the ellipsoid trapezoidal area is obtained using the improved algorithm. The ellipsoid area of large trapezoidal block can be obtained, and the ellipsoid area of arbitrary polygon can be easily solved also by the improved algorithm.