The parallel query optimization for multi-join expressions is one of the key factors to improve the performance of database systems. In this paper, an approach to solve the problems of the parallel query optimization for multi-join expressions by adopting GA algorithms is proposed. To improve the execution efficiency of the query processors, the authors exploit heuristics to seek the optimum parallel scheduling execution plan for multi-join expressions. The detailed testing results and performance analysis are presented.The experiment results show that the GA algorithm with heuristic knowledge is effective for parallel query processing of multi-joins,and plays an important role in improving the performance of database systems.