Multiple travelling salesman problem (MTSP) is a typical computationally complex combinatorial optimization problem,which is an extension of the famous travelling salesman problem (TSP). The MTSP can be generalized to a wide variety of routing and scheduling problems.It is known that classical optimization procedures are not adequate for this problem.The paper makes the attempt to show how the ant colony optimization(ACO) can be applied to the MTSP with ability constraint. In this paper,we compare it with MGA by testing several standard problems from TSPLIB.The computational results show that the proposed algorithm can find competitive solutions even not all of the best solutions within rational time, especially for large scale problems.