The traffic grooming in optical network is studied in this paper.Using auxiliary graph,the traffic grooming problem can be solved as a routing problem.Traditional auxiliary graph is complex and the bandwidth utilization of light path is not high.So a new auxiliary graph is proposed in this paper.The new auxiliary graph can use the light path more efficiently and can avoid inefficient routing.In order to decrease the complexity of the dynamic traffic grooming algorithm,a simplified k shortest path routing algorithm is proposed.A series of traffic grooming schemes are put forward based on the simplified k shortest path routing algorithm.The simulation results show that the new auxiliary graph and its grooming algorithm can reduce the blocking probability effectively.