The disclosure provides an integrated separation unit for microplastics in the coastal sediments and a collection method of microplastics, belonging to the technical field of water treatment. The unit includes: a holder, a separation cylinder, a collection bottle, a central baffle plate, a baffle plate control knob, a stirring propeller, a motor, a cylinder switch, a filtration screen, a welding nozzle, a filter membrane and a vacuum pump. Using this unit for microplastic collection has the advantages of easy operation, economical and environment-friendly, high separation efficiency, and high durability.