Microgrooves with a pitch at wave length level are increasingly needed in the optical system. Conventional, the microgroove forming accuracy is low due to the incomplete filling of the material in the cavity of microgroove mold, and surface flaws occur easily due to the adhesion of the resin material to the mold surface. In this research, the response behavior of resin material subjected to alternating stress is resolved based on Generalized Maxwell model. Finite Element Method (FEM) simulation is carried out to test the microgroove forming effects under the pressing condition without and with ultrasonic vibration. An ultrasonic assisted pressing machine is developed and used to fabricate microgrooves on methacrylic resin surface. Form accuracy and surface quality of microgrooves are confirmed to be improved by comparing the ultrasonic assisted pressing with the conventional forming.