When two or more radars with separated space positions and overlapping coverage are used to detect the targets, a radar network is formed. Radar networking can complete data information sharing, improve the reliability of early warning, identification, positioning and detection functions, and improve system functions. Due to the differences in frequency band, platform, system and polarization form of each radar, the deployment process is highly comprehensive. In this paper, a calculation model based on radar detection probability is established for optimal deployment of netted radar. The model takes into account the number of pulse accumulation of pulse radar. The PSO algorithm with variable weight is used to quickly calculate the optimal solution. The best deployment scheme maximizes the detection probability of the netted radar. The simulation results show that the model can describe the detection probability of the netted radar against targets at different distances, and it has important reference value for the optimal deployment of the actual radar network.