The system performance of the radar network based on the track fusion is dependent on the capacity of the single radar. The detection fusion of radar network is studied according to the fusion theory, which would improve the detection probability of the low RCS targets by signal integration. The system architecture is presented firstly; with engineering factors considered, the methods of centralized detection and distributed detection are analyzed, and the advantages and disadvantages are indicated; the related synchronous technologies are studied in detail; finally the development tendency is prospected.