As one of the most fundmental, critical and challengable problems in PDC (parallel distributed computing), task scheduling has great influence on the execution efficiency of PDC. The existing heuristic task schedulings based on static task priorities always use it as processor selection policy to make the current task have earliest start execution time. On the basis of analysis of the mechanism in priority-based heuristic task scheduling, the authors illustrate the drawbacks of the processor selection policy mentioned above, and propose a new processor selection policy, i.e, to make the successor of the current task have the earliest start time, and give the corresponding restraint.