Time-slotted optical burst switched network is a new paradigm to support IP over WDM by combining Time Division Multiplexing and Optical Burst switching technology. This paper presents a framework to evaluate blocking performance of time-slotted OBS networks with multi-fiber wavelength channels. The model is applied to analyze effect of the change of network parametesr as well as multiple-class traffics in the TS-OBS network. The effectiveness of our model is validated by simulation results. Our study shows that multi-fiber TS-OBS network is a potential technique to provide acceptable blocking performance for future Internet services.