Objective To establish a detection method for the detachment of polyethylene microplastics during the use of disposable paper cups with polyethylene inner coating.Methods The method employed hydrogen peroxide digestion， sodium bicarbonate solution ultrasonic removal of residual hydrogen peroxide， ethanol dispersion， and then silver membrane filtration to collect polyethylene microplastics from paper cup water samples. Micro-Raman spectroscopy was applied to detect the microplastics on the filter membrane. And scanning electron microscopy （SEM） and micro-Raman Spectroscopy were introduced to study the pre-treatment processes.Results After optimization， the concentration of 23% （v/v） hydrogen peroxide could eliminate the interference of matrix in samples. The addition of 5.0 g/L sodium bicarbonate， combined with ultrasound， couldtotallydecompose the residual hydrogen peroxide in the digestion solution. Adding 25% （v/v） ethanol to the digestion solution could effectively disperse microplastics in the system， so that microplastics were then uniformly dispersed on the surface of the silver film during filtration. Further， the detachment of polyethylene microplastics from disposable paper cups was quantitatively detected. The detection limit was calculatedas 1 877.7 p/L， the relative standard deviation was 9.7%-27.5%， and the recovery rate was 98%-111%. Results indicated that disposable paper cups coated with polyethylene could release 2 500-20 000 p/L （>2 μm） microplastics in water.Conclusion Compared with traditional pre-treatment processes， our method could solve the problems of silver film corrosion and uneven dispersion of microplastics. The results of real samples detection suggested that disposable paper cups coated with polyethylene can bring health risks by microplastics during use.