Abstract: Certain classes of plastics are widely used in the industry and life, which yield progressively fragments as microplastics smaller than 5 mm.Microplastics can be present on the shorelines, in the oceans and even in the remote arctic ice.There are concerns it may bring durable hazards to the marine environment.Microplastics in the offshore marine environment mainly concentrate in the surface seawater, on the beach and in the sediments, and finally deposit in the deep sea as a sink after long-term migration driven by the currents.Currently methods used for the identification of microplastics are mainly limited in the laboratory and mostly depend on manual operation.Hence methods appropriate for automatic in-situ monitoring of microplastics in the marine environment is in urgent need.In this review, the application of instrumental analysis techniques in the collection, sample processing and analysis as well as the characteristics and applicable conditions were summarized.Therefore, burning issues are put forward in order to help establish the direction and theoretical support for the long-term automatic monitoring of marine microplastics.