The invention discloses a microsatellite portable 422/CAN isolation tester which comprises a FPGA module, a CAN control module, an optical coupler isolation module, a CAN driving module, a 422 drivingmodule, a USB interface module and an isolation DC module, wherein the FPGA module is respectively connected with the CAN control module and the USB interface module; the CAN driving module is connected with the CAN control module by the optical coupler isolation module; the 422 driving module is connected with the FPGA module by the optical coupler isolation module; the CAN driving module and the 422 driving module are respectively connected with a CAN interface and an RS422 interface on a satellite; by constructing the controllers of two serial ports on software, RS422 data is directly converted into RS232 data to be directly transmitted to a PC machine; and the CAN control module implements mutual conversion of a CAN bus protocol and an RS232 protocol. According to the tester, each module takes power from the PC machine by the USB module, and the CAN driving module and the 422 driving module take power by the isolation DC module. The microsatellite portable 422/CAN isolation testercan implement testing on a ground checking interface of a microsatellite satellite-borne machine, is convenient for wiring, and does not need to install special communication protocol software on thePC machine.