This paper introduces an enhancements to Ant Colony system, which is considered one of the most successful ant algorithms used to solve combinatorial optimization problems. Network Planning is the problem of how to plan the infrastructure network in the new city. This paper deals with optimization algorithms for network design problem. The objective is to design a distribution network at a minimum cost that satisfies the demand and constraints required by the subscribers. This approach uses the idea of an ant group to represent a solution and can assist the solution of large networks that cannot normally be solved to optimality. The algorithmic implementation of the proposed algorithm is described and computational experience is reported. Results demonstrate the effectiveness and flexibility of the modifying algorithm. Comparisons with related work are presented showing the advantages of the purposed algorithm introduced in this paper.