This paper discusses a safety inspection system that applies x-ray technology to check passengers on some important sites, such as airports. In the actual inspection, passengers are required to take off their shoes to be checked at the airports. This system will realize instant inspecting function, utilizing the x-ray’s penetrating property, while people pass with shoes on. X-ray generating module, inspecting module, information receiving and converting module as well as the processing module constitute all of the system. The X-ray generating module brings out x-ray of appropriate and safe dose. The inspecting module introduces infrared detection method to realize automatic checking flow. A LLL system is developed as the third module in which information is collected and digitized to deal with later. Then the processing module is to achieve, process information and show the results by means of information pick-up, image processing, remote conveying and controlling, building bank of information etc. The system improves inspecting speed and accuracy. At the same time, it extends the detection sorts largely so that not only metal but also other organic substances can be perceived. Finally we give a resolution expression of this kind of system and discuss the influence factors. Then some approaches to improve the system’s performance have been presented, which have great significance in improving and developing this kind of system.