With different task mapping and scheduling will lead to different time consumption and energy consumption on heterogeneous multiprocessor systems, using appropriate task mapping and scheduling algorithms can save more energy. In this paper, we propose a new method to solve the task mapping problem. The algorithm consists of two elements: An intelligent approach to assign the execution orders of tasks by task level, and an allocation algorithm based on chemical-reaction-inspired metaheuristic called Chemical Reaction Optimization (CRO) to map processors to tasks. The results show that it can use less time to reduce more energy consumption.