Abstract: Due to array application requirement of power amplification T/R module, how to allocate cooling resources so that temperatures of these T/R modules can uniformly distributed is an urgent problem to be solved. In this paper a thermal management system of the power amplification T/R module arrays based on active flow distribution is studied by thermal simulation and experiment. Each array is embedded in a miniature valve to control the cooling resources by temperature feedback and PID (Proportion-Integral-Differential) algorithm. The results indicate that this thermal management system can enable the cooling resources to be distributed according to requirement so that the temperature distribution of the arrays is uniform.