In this paper introduced solving interval based Assignment problem in another way by using complete bipartite graph directly with algorithm. The edges are represented the cost of assigning person to task, the nodes are represented the tasks and persons. The solution will be by choosing the minimum cost (edge) from the costs (edges) and delete the selected edge as well as nodes associated with the corresponding edge, then delete all other edges associated with the nodes. Also, compare the optimal solution with this new interval method and an existing interval assignment method.