In view of maintainability and maintenance timing for T/R components of phased array radar in which the fault number is less than 10%, a rule of channel fault forming the influence on DBF is analyzed, and a maintenance strategy to keep radar performance from degradation is proposed. First, mathematical models of transmitting DBF and receiving DBF based on LMS algorithm are established based on the structure of planar array. And then, the transmitting and receiving beam forming performance of T/R components are verified in both normal condition and partial failure through the simulation, and the influence of fault number and fault region on receiving DBF performance and radar detection performance is analyzed by using five indicators. Finally, its internal law is analyzed, and the maintenance strategy is putted forward, providing theoretical basis and decision support for scientific and precise maintenance and operational effectiveness.