Based on the STM32 library function, this design is developed a good docking with the engine, without changing the engine's original ECU. Only on the test bench, this design which connected to the device can enter the injection pulse width, so as to control the engine mixture concentration. Using this experimental device, the fuel adjustment characteristic experiment was completed on the existing engine test bed, which verified that the experimental device developed by this design had good adaptability in use. In this way, universities and research institutes can use this experimental device to easily complete the fuel adjustment characteristic experiment, and can also provide a convenient tool option for the calibration and optimization of the engine pulse spectrum.