A rapid thermal cycling molding technology with electric heating and water cooling was developed to improve surface quality of microcellular polyoxymethylene (POM) cover plates injection molded using supercritical nitrogen as physical foaming agent.The temperature distribution uniformity on the whole mold cavity surface was obviously improved via optimization design.The effect of mold cavity surface temperature (TM) on the cellular structure and surface quality of the microcellular POM cover plates was quantitatively investigated and relevant mechanisms were analyzed.The results demonstrated that raising TM resulted in thinner unfoamed skin layer but somewhat larger and unevenly distributed cells in the microcellular POM cover plates.Raising TM from 40℃ to 150℃ greatly improved the surface quality of the cover plates and effectively reduced their surface roughness by about 85% without a significant increase in cycle time.The surface defects that usually occur in conventional microcellular injection molding were eliminated at a TM of 150℃.The TM should be appropriately high (about 130℃) to improve surface quality of the microcellular POM cover plates and keep good cellular structure simultaneously.