The invention discloses a high-gain white plastic projection screen. The projection screen comprises a first motor, a second motor, a screen shaft, a shaft sleeve, a transitional screen and a white plastic screen, wherein the rotary shafts of the first motor and the second motor are arranged oppositely, and are in transmission connection through the screen shaft; the upper end of the transitional screen is fixed on the screen shaft while the lower end is connected with the white plastic screen; the exterior of the screen shaft is sleeved with the shaft sleeve, and a long slit used for allowing the transitional screen and the white plastic screen to pass through is formed in the shaft sleeve; a first side screen and a second side screen are fixed at the left and right ends of the white plastic screen; and the front surfaces of the first side screen and the second side screen are coated with carbon nanotubes or carbon black. According to the high-gain white plastic projection screen provided by the invention, based on the characteristic that incident light rays on the two sides of the white plastic screen cause diffuse reflection easily, the first side screen and the second side screen are provided to lower the light ray entry from the side screens of the main screen of the white plastic screen so as to improve projection quality.