The modular design method is adopted for the hardware circuit of electronic control unit on the high pressure common rail aero piston engine, which is helpful for the electronic control hardware system to adapt to the development trend of functional integrated chip. As the core of Infineon 32-bit microcontroller chip, it was modularly designed from the whole to the details by including the 3.3 V and 5 V power supply, MCU crystal oscillator power supply, 0 ~ 5 V sensor signal conditioning, high and low side power driving of the actuators, PCB layout and so on. After PCB printed circuit board and manual welding of electronic components, the circuit hardware system was verified on the engine bench. In the experimental results, it was analyzed that the 0 ~ 3.3 V voltage limiting and variable frequency square wave conversion of the signal conditioning module of crankshaft and camshaft sensor, the maximum 5 A power driving of the high-side MOS tube of the high pressure pump metering solenoid valve and the driving Peak-Hold transient current of the 24 ~ 48 V hybrid half-bridge MOS tube of the fuel injectors.