Abstract: The paper introduced composition and working principle of the long array infrared scanning position system in open space,expounded design of electronic displacement scanning circuit with line by line and interference processing of strong sunlight infrared and implementation of fault detection of infrard module, as well as gave software design of the system.The system uses the technology of electronic displacement high-speed scanning with line by line,the technology of automatic detection of system fault and many kinds of anti-interference measures of outdoor strong sunlight infrared to identify fault position and fault type of the infrared module of the system,which realizes quick and accurate position and improves ability of anti-interference of the system and stability,reliability and maintenance of the position.The system uses Delphi to develop the main control software of the system in order to finish the functions of display,output,setting of working parameters and state detection of the position result.The system has been applied in actual projects,which has good effect.