Considering comprehensively the five parameters affecting threat degree, the criteria and methods for assessing the threat degree of radiation source are given. A comprehensive priority algorithm (highest threat,highest priority and earliest deadline first, HTHPEDF) is proposed in the design of the task priority of the passive radar with the radiation source threat parameters which can be dynamically adjusted according to the degree of the threat of radiator. On this basis, the task adaptive scheduling implementation, the performance evaluation and the scheduling cost function are designed. The simulation results show that the algorithm obtains higher task scheduling performance with lower cost and has certain advantages for enhancing task scheduling ability.