The invention discloses a multifunctional plastic processing device. The multifunctional plastic processing device comprises a material protective connecting port, an electric instrument control system, a microwave generator, a kneading machine, a screw discharging system and an equipment base. According to the multifunctional plastic processing device, the microwave generator is adopted, on the one hand, heat energy is supplied to plastic material processing, one the other hand, microwaves are adopted to enable waste rubber to be subjected to desulfuration splitting decomposition, and reclaimed rubber is produced; and the microwave generator is matched with a stirring paddle of the kneading machine and the screw discharging system for working to enable plastic mixing and the modifying processing reaction to be completed in one piece of equipment, and automatic discharging is conducted, so that the labor intensity of workers is greatly relieved.