Abstract: The paper presents a method of Hardware-Software partitioning using task graph. By the method, first we calculate the inclination of area, time, communication and the ratio of all nodes, used to calculate the heuristic parameters. Then according to the heuristic parameters, we adopt heuristic branch and bound algorithm for partitioning the system to obtain both the feasible solution and the best solution. We coded the algorithm described in the paper as well as other two algorithms, RECOD and UNRET. Then we compared the performance of these three algorithms by calculating the minimum initiation internal, the initiation internal and the calculation time for the systems respectively with 10, 15,20,25,30 nodes. The algorithm proposed in the article is suitable for the systems in middle or small scale with a coarse granularity partitioning of task graph.