The thermoplastic resin has a huge molecular weight and high viscosity of its melt， so there are some problems in the preparation of composite materials by hot melting method， such as poor fluidity of resin and easy formation of composite defects on the microscopic scale. Using in-situ polymerization to prepare thermoplastic composites can not only avoid the above problems， but also use the forming method of thermosetting composites， so as to achieve high efficiency and low-cost manufacturing of thermoplastic composites. Therefore， in-situ polymerization thermoplastic composites have broad application prospects in the field of composite materials. Based on several in-situ polymerized thermoplastic resins， this paper describes the research status of composite material properties and forming processes， and puts forward four research directions in view of the existing problems： Coupling of modification process and forming process， control of environmental cleanliness of polymerization and sensitivity of polymerization to impurities， control of heat release temperature of polymerization reaction， regulation of pot life of resin.