As an engineering plastic, polyoxymethylene (POM) possesses good comprehensive performance, such as good mechanical property, resistance to abrasion, fatigue resistance, resistance to chemicals and self-lubrication performance. One of the important applications of POM is in fabrication of the transmission parts, particularly the micro transmission parts e.g., microgears, etc. For some special fields such as high precision watch and aerospace industries, the micro transmission parts applied generally require the substantially improved self-lubrication performance and mechanical property. So, it is very necessary to conduct a modification on POM to enhance its properties. Compositing of molybdenum disulfide (MoS2) with POM is a promising solution. However, the dispersion of MoS2 fillers in polymer matrix could be a challenge. In this paper, a novel solid state shear milling technology was used to prepare the POM/MoS2 nanocomposite and subsequently the microinjection molding investigation was also carried out. The results show that the nano-scale MoS2 exfoliated platelets with perfect dispersion in POM matrix is successfully achieved. The obtained POM/MoS2 nanocomposites exhibit the obviously enhanced tribological property and mechanical property. In addition, the microparts show four layers with different crystallization morphologies, where the transition layer mainly consists of shish-kebab structures. The mold cavity size and processing parameters (injection speed and mold temperature) were found to have dramatic influence on the orientation structure, morphology and mechanical performance. This work is supported by the Program for Youth Team of Sci & Tech Innovation Research in Sichuan Province and the Project of State Key Laboratory of Polymer Materials Engineering (Sichuan University) (sklpme2016-2-01).