Novel multi layer and stripe morphology were investigated in micro-injection molded isotactic polypropylene gear. The annealing treatment was performed on the gear tooth under different temperature and time to control its morphology evolution. The effects of the mold temperature of micro-injection molding on the microstructures and mechanical properties of isotactic polypropylene gears were studied. The micro-injection molded gears present a skin-core type of morphology. The core layer is much thicker than the core and shear layers. Nanoindentation tests show that the modulus decreases along the flow direction and increases with increasing mold temperature. The highly oriented shear layer has the highest nanoindentation modulus compared with the skin and core layers.