Abstract: A method which includes a flashing process and a process for extruding thermoplastic plastics is provided for achieving more thorough devolatilizing of the solutions of thermoplastic plastics, to ensure that the solutions of thermoplastic plastics are able to be worked continually, wherein the accoustic treatments are introduced into both processes to increase the efficiency of removing volatile components and thus leads to the decrease of the processing time for extruding thermoplastic plastics. In the flashing process, the ultrasonic horns are arranged to scatter the feed stream of the solution which increases the devolatilizing surface of the polymer fluid and, simultaneously, to enhance bubble formation and produce strong agitation in the polymer fluid, thereby increasing the devolatilizing efficiency. In the process of extruding thermoplastic plastics, the ultrasonic horns are arranged in the extruder to enhance both formation and rupture of bubbles, thereby increasing the devolatilizing efficiency.