Abstract: A set of mixed-signal read out system was designed for the phoswich detectors of the γ-ray burst monitor in the SVOM satellite, which was used to obtain the amplitude and the width of the voltage pulse that came from the GRM phoswich detector, and classify the signals. The FPGA was used to control the timing in the system, high-speed peak holding circuit was used to get the peak of voltage pulse, and the RS232 interface was used to complete the data exchange between the system and the PC. The test results show that this design can achieve the data acquisition and the discrimination.