Abstract: Aiming at the arithmetic of the sample covariance matrix inversion with Cholesky decomposition in the space-time adaptive processing(STAP), a parallelizing construction of the arithmetic module based on FPGA is designed for matrix inversion with Cholesky decomposition, containing three sub modules of Cholesky decomposition, triangle matrix inversion, and triangle matrix multiplication. After measuring and simulating, the relationships of order of the matrix,parallelism degree,occupied resources of the FPGA, calculating time, and arithmetic precision are analysised detailedly.