FMM is an efficient algorithm in computing N-body problem. This paper firstly partitions the FMM into 8 procedures. Based on the analysis the running time and computing type of each procedure, we choose key procedures accelerated on FPGA, and then we present the speedup ratio of each accelerated procedure through experiments. According to the FPGA acceleration effect on the procedures, a multi-level acceleration project is proposed. Finally we put forward a hardware architecture of FPGA accelerated high performance computer.