The invention relates to a modularized vehicle door with steel, aluminum and plastic mixed. Compared with a total complex structure of a traditional vehicle door, according to the modularized vehicle door with steel, aluminum and plastic mixed, the original complex vehicle door structure is modularized, and the vehicle door structure is divided into three functional modules which include a vehicle door outer plate, a vehicle door frame, a vehicle door inner plate and an accessory module. According to the functionality of all parts of the vehicle door, traditional vehicle door modules are functionalized, and good vehicle door manufacturing and assembling manufacturability is achieved. The modularized vehicle door with steel, aluminum and plastic mixed is specifically characterized in that the vehicle door outer plate is not a main stressed part in the vehicle door structure, the strength and rigidity requirements are moderate, and the purpose generally lies in the effect that the functional requirements for meeting external shapes are improved; the vehicle door inner plate is not a main stressed part, either, and can be made of composite materials or plastic. According to the modularized vehicle door with steel, aluminum and plastic mixed, factors in all the aspects of strength, rigidity, appearance and weight are taken into comprehensive consideration, the vehicle door outer plate can be made of thinner metal material plates and aluminum alloy materials, and the aluminum alloy materials are light, small in specific gravity, high in strength, good in ductility, and high in corrosion resistance and meanwhile has good forming performance, machinability and the like.