Abstract: The on-line detection of a certain photoelectric tracking system was realized through the computer simulation platform, however, the simulation platform is large in volume, inconvenient in carrying and complex in installation. In order to solve the problem of using in field, a portable photoelectric tracking system on-line detection device was designed and implemented.The device adopts the ARM embedded platform based on WinCE operating system and divides the working state detection into one system-level module and multiple component-level modules, which can conduct testing through module according to actual needs, thereby the CPU load and detecting device consumption can be reduces. Actual verification show that, the device can realize real-time on-line detection of the detailed state of photoelectric tracking system and accurately locate the fault site to achieve the purpose of quickly repairing the fault.