The traditional fault diagnosis(FD) system of construction machinery(CM) is not competent for the task of FD of modern construction equipment because of its own bottleneck. Nowadays, the computer network information technology and wireless communication technology are highly developed, so it is the development trend and trend of mechanical FD technology to design a FD system based on wireless communication network for CM. The FD system in this paper is constructed based on wireless communication network and fuzzy FD method, which is used for FD and maintenance of CM and equipment, and realizes intelligent collection of mechanical fault data in construction site. By testing the performance of the system and the accuracy of the FD model, it shows that the system performance test is good, and the FD rate is over 90%, which can meet the system objectives and requirements.