Abstract:This paper studies the theory and method of constructing virtual spherical harmonic of municipal geoid. First, we select the center point and radius of the build area. Then, the observed data are preprocessed, and the numerical range and location information of the observed values are statistically analyzed. Secondly, the coordinates of the observed values are transformed from geographic coordinates to spherical crown coordinates, and then to a virtual spherical coordinate system. Finally, the municipal geoid is constructed according to the virtual spherical harmonic method. The polynomial fitting, neural network and virtual spherical harmonic method are used to construct the sampling points in Nanchang city. The results show that the virtual spherical harmonic method has the smallest fitting RMS value, which is only 0.308 cm, and the best effect.