The invention provides a hardware blocking layer of onboard software and an onboard data communication method, and belongs to the field of space vehicle data communication. Interface set with corresponding functions are designed targeted at the functions of hardware equipment to form the hardware blocking layer for the onboard software; the interface set comprises a standard input/output interface function, calling parameters of the interface function comprise equipment property parameters and data communication interface parameters; and the interface function can achieve a certain function and has a return value. When the onboard data communication method disclosed by the invention is used, application software only need to provide the equipment property parameters and communication interface parameters when necessary, then the interface function is called to finish the communications with the hardware equipment. The hardware blocking layer for the onboard software and the onboard data communication method disclosed by the invention are mainly applied to communications between the hardware equipment and the upper software of the space vehicle.