In this paper, VHDL is applied to design the scanning system of LIDA. The MAX7000 series is selected to achieve the function. Due to the application of the VHDL and the Complex Programmable Logic Device(CPLD), the system complexity and design difficulty are reduced and the efficiency is enhanced. Some source codes are presented in the paper, which have been synthesized and simulated. At last,questions during the design are emphasized and analyzed.