FMCW(Frequency Modulation Continuous Wave) Radar is very useful for vehicle collision warning system because of the simplicity. In this work, a signal processing part of FMCW vehicle radar system is implemented with flexibility using DSP, FPGA, ADC, and DAC so that the system could adopt lots of algorithm and could be improved through road test. It is shown that the system meets basic requirements as designed, and finds some problems in road test. We briefly discuss the problem which are caused by shadow effect from overlapped target and the distortion of beat frequency from the nonlinearity of VCO and the RCS of vehicle.