Whereas crystallinity is important in crystalline polymers, the scale and the ratio of the short-range structure is important in amorphous polymers because it affects mechanical and optical properties. This work detected short-range structures inside the injection molded PMMA part. Effects of cooling rate on the ratio of short-range structure formation and shrinkage of the molded PMMA part were investigated. Effects of laser annealing on the short-range structure inside the molded PMMA part were also inspected. Two fixed mold temperatures, 80�Ž and 10�Ž, were used in the injection molding experiment. A static light scattering apparatus with laser light sources of wavelength 405 and 633 nm was used to detect short-range structures inside the molded PMMA parts. For annealing, a Neodymium laser of wavelength 1,064 nm were employed. Experimental results showed that the formation of short-range structure in the injection molded PMMA part can be detected by measuring the variation of light scattering intensity. Injection molding with a high mold temperature causes more formation of short-range structures and shrinkage in the PMMA part than that with a lower mold temperature. Furthermore, the ratio of short-range structure distributed inside a molded PMMA part is non-uniform, which results in slight differences in local shrinkage. Laser annealing can be used to regulate the short-range structure inside the molded PMMA part and uniform the shrinkage of the part.