The influence of different RWA (Routing and Wavelength Assignment) approaches on the optimal performance of p-cycles in WDM networks without wavelength conversion was investigated. The method of load balanced was proposed to achieve nearly uniform distribution of working capacity over the wavelength layers in order to reduce total network capacity. Five RWA approaches were considered,including Dynamic Layered Generalized RWA (DL-GRWA),Shortest Path RWA (SP-RWA),Dynamic Layered with load balanced (DL-LB) Shortest Path with load balanced (SP-LB) and Fixed Wavelength with load balanced (FW-LB). Simulation results show that by means of every approach the total network capacity decreases with the increase of the maximum allowed cycle hops. Among them,SP-LB approach can minimize the total network capacity.