Abstract: To meet the demand of high-speed readout of multi-channel signals from micro pattern gas detectors, a digitization system is designed for the 128-channel preamplifier chip APV25 based on the field programmable gate array (FPGA) Spartan-6. In this system, the serial analog signal output by the APV25 is digitized by the analog-to-digital conversion (ADC) chip ADS5242. After the serial-to-parallel conversion by the Spartan-6, the data are acquired, buffered and packaged to the user datagram, and then sent to the computer via the gigabit ethernet for storage and analysis. In the test, the system reaches a maximum sampling rate of 280 kHz for the APV25, and the pedestal noise is as low as 716 electrons. The linearity of the charge response is good when the input amount of charge is less than 75 000 electrons. This system is expected to be used in the multi-channel radiation detection system in space thanks to the radiation tolerance of the APV25.