Abstract: The structural characteristics of thermoplastic parts was analyzed in the cases of a toilet seat and cover. The structure of the injection mold was optimized by a Moldflow software, and then the mold was designed by UG software. The structural characteristics and conducting process of the mold were introduced. The toilet seat and cover were injectionmolded by the mold. The mold joint was designed only in the periphery of the plastic parts. Molding of the side holes for the toilet seat and cover was achieved by using lifter and angle pin respectively. The guide unit is consisted of guide pillars, fourcorners side positioning and chain. The injection mold of the toilet seat and cover had a rational structure and high reliability.

Key words: toilet seat, cover, injection mold, Moldflow software, design