Abstract: Aiming at the problem of synchronous image acquisition in potato dynamic grading system，a synchronous acquisition method based on Gigabit Ethernet was proposed.Three cameras were used for synchronous acquisition from three directions of potato to be tested.LM358 was used to design a primary in-phase voltage amplifier circuit to amplify the PWM signal generated by STM32 to control synchronous operation of three cameras.Secondary design and development were carried out on Visual Studio 2013 with C++ to realize functions of synchronous acquisition and image storage of three cameras.Experimental results showed that synchronous frame rate of three cameras reached 12 frames/s，which could meet requirements of image acquisition in potato dynamic grading system.