Nasopharyngeal tissue modeling is the base of computer simulation of nasopharyngeal carcinoma therapy. Nasopharyngeal tissue was segmented by a combine of doctor's sketch and mathematical morphology method. A color lookup table was made for the fast recognition of about sixty tissues. For there are many tissues around nasopharynx, level-of-detail tactic is used to reconstruct different tissues by different methods. The improved marching cubes algorithm was used to reconstruct the nasopharyngeal tissue needed to be subtly display. The less important tissues were reconstructed by contour-connecting method. A series of simplified models were made to fit the simulation. Ray casting method was used to down sampling data of tissues that can show space position. The level-of-detail tactic reconstructed subtle model of important nasopharyngeal tissues while show the position of other nasopharyngeal tissues. It meets the needs of nasopharyngeal carcinoma treatment computer simulation.