How to utilize wavelength conversion is the key factor in improving the blocking performance in wavelength-routed all-optical networks. The paper studies the novel conversion wavelength architectures and methods, and proposes a hybrid wavelength conversions, which can reduce the number of wavelength converters and preserve the performance. The paper examined five different wavelength converter utilization schemes and presented the best wavelength converter utilization strategy with simulation. Considering hybrid wavelength conversion and wavelength converter utilization strategy, a scheme of optimal wavelength converter placement in optical networks is presented by genetic algorithm and the simulation results demonstrate that it can hold the network performance and need not increase the number of wavelength.