The invention discloses an FPGA-based onboard system realization method. The method comprises the steps of S1, establishing a processor module, wherein the processor module comprises a controller anda data path; S2, establishing an FPGA device module, wherein the FPGA device module comprises a PS / 2 interface, an RS232 interface, a VGA interface, a 7-section LED display screen, an LED display screen, a Switch, a Button, an on-chip ROM, a bus interface and IO control logic; S3, establishing an onboard memory module, wherein the onboard memory module comprises a VRAM and a memory; and S4, combining circuits of the processor module, the FPGA device module and the memory module into a stream file, and programming the stream file in an FPGA. The method has the advantages in two aspects that therealization efficiency is high: hardware resources provided by the FPGA are rich, and designed computer system hardware can be quickly realized on the FPGA, so that the realization efficiency is higher; and the flexibility is high: the FPGA is reconfigurable, so that when partial hardware parameters of the computer system hardware are changed, reconfiguration can be performed during operation, namely, the computer system hardware realized through the FPGA is more flexible.