The invention discloses a projection type planar waveguide helmet-mounted displayer. The projection type planar waveguide helmet-mounted displayer comprises a mini-type display device, a projection optical system, a planar waveguide and a reflection type projection screen, the planar waveguide is internally provided with an optical coupling-in end and an optical coupling-out end, and light rays sent by the mini-type display device are imaged through the projection optical system and are transmitted to enter the optical coupling-in end of the planar waveguide. The optical coupling-in end reflects the received light rays to enable the reflected light rays to be totally reflected between two reflection planes of the planar waveguide many times to be transmitted to the optical coupling-out end of the planar waveguide. The optical coupling-out end reflects the received light rays to the reflection type projection screen. The reflection type projection screen reflects the received light rays to enable the light rays to return according to the original path, then the light rays are transmitted to the human eyes from the optical coupling-out end of the planar waveguide. By means of the method, the problem that an existing helmet-mounted displayer is large is solved, the observing view field can be expanded by designing different structures, and the designing difficulty of the projection optical system is reduced.