Plastic film has allowed manufacturers to meet varied marketplace demands. Typically, its usage can be divided into two general categories-packaging (food, nonfood and other) and nonpackaging. The microplastics emission resulting from wearing of plastic film is unavoidable in the process of production and use. Currently, no reliable method exists for measure emission factor (EF) of microplastics by mechanical abrasion (MA). In the present study, a simple but effective approach to quantify EF of microplastic by MA was developed. Specifically, the relative light transmittance (RLT) of the plastic film is decreased with increase of MA degree. This quantitative relationship between the two factors can be applied to determine EFs of microplastics induced by MA. The method developed in this study is easy and feasible, but it still has limitations in the standpoint and range, the direction of worthiness of theory.