The Ant Colony System (ACS) algorithm is vital in solving combinatorial optimization problems. However, the weaknesses of premature convergence and low efficiency greatly restrict its application. In order to improve the performance of the algorithm, the Hybrid Ant Colony System (HACS) is presented by introducing the pheromone adjusting approach, combining ACS with saving and interchange methods, etc. Furthermore, the HACS is applied to solve the Vehicle Routing Problem with Time Window (VRPTW). By comparing the computational results with the previousfindings, it is concluded that HA1CS is an effective and efficient way to solve combinatorial optimization problems.