In this paper, the placement problem of wavelength converters in DWDM (Dense Wavelength Division Multiplexing) networks with arbitrary topologies is investigated. We could settle the problem easily by considering the two sub-problems of routing selecting and converter placement simultaneously. A reasonable path algorithm in which load balance and shortest path are considering together was proposed. Based on this model, we presented three simple algorithms A,B and C for wavelength converter placement. Simulation results on the basic characteristic of converter placement of EON and NSFNET are presented. With the three algorithms, the cost (including routing selecting and placement of WC) of optimizing network has been greatly reduced but the blocking performance has not been reduced.