Abstract: Ultra-high resolution seismic exploration based on sparker has become more important with time in marine regional geological survey and engineering geophysical exploration in China. In practical performance, the distance between sparkers is usually in a scale of centimeter, and thus it is difficult to carry out numerical simulation for spark gun array. To solve this problem, based on the conventional variable grid finite difference algorithm, this paper proposed a multi-grid strategy in the numerical modeling of spark gun array, and realized the high-precision 3D numerical modeling of the spark gun array based on the multi-grid algorithm. Numerical simulation experiments show that comparing to conventional staggered-grid finite difference numerical simulation, the multi-grid finite difference numerical simulation algorithm can significantly improve the computational efficiency and reduce the memory consumption. At the same time, it can effectively suppress the false reflection in the conventional variable grid algorithm, and realize the high-precision numerical simulation of the spark gun array.