Autonomous test is one of the key technologies for building spacecraft autonomy. For the problem of task priority scheduling in real time operation system, a mix scheduling strategy with software-hardware cooperate was presented. After analyzing the influence factors of task importance in the complex engineering background, a synthesizing estimate index of task importance was proposed to assign priorities statically. The huge task set was clustered by self-organizing feature map afterwards. Based on this work, a priority arbitrage agent was established to reassign priorities. Then the reliability criterion was introduced to realize the priority dynamical scheduling based on FPGA(field programmable gate array). The experiment shows the strategy has reference value for autonomous system to assign priority resource rationally and to schedule test task in high speed.