This paper has introduced a new design method of PXI peak power analyzer. The PXI peak power analyzer’s compact architecture uses PCI interface chip, FPGA DSP. It takes full advantage of FPGA's agility and DSP's data process ability. The analyzer can be used to acquire and process complex microwave peak power signal. Many methods of sampling, calibration and compensation are used, in order to make automatic and accurate measurement of input pulse modulation signal for many parameters. The speed of calibration is improved more than 36 times, and the accuracy optimization is up to 3%. In this paper, the system frame, machine principle and software detailed design are discussed. Many key techniques are emphatically described, including data acquisition, power calibration and power compensation.