Abstract: Optical Burst Switching (OBS) is considered as an efficient switching technique for the next generation optical networks. QoS (Quality of Service) support is an important issue in OBS networks. This paper focuses mainly on the QoS algorithms based on wavelength grouping schemes, and proposes several new QoS algorithms. These algorithms can adjust the wavelengths used in each class dynamically, according to the variation of its traffic. Simulation results and comparisons with the existing algorithms show that these algorithms can provide better differentiated service, decrease the burst loss probability and improve the channel utilization.