The present invention relates to a piece of assembly auxiliary equipment of 3D stereoscopic image projection playing system, comprising a hanger frame assembly, a polarized light projection device and a metal curtain. The hanger frame assembly has a main frame, wherein three layers of tray plates with adjustable front and back pitch angles are disposed on the main frame; the upper and middle layers of tray plates are respectively used for stacking and fixing two projectors up and down; horizontal slots and location screw holes for plug-in mounting and fixing a polariscope tray are disposed on the upper and lower layers of tray frames; the polarized light projection device comprises two polariscope trays combined with the upper and middle layers of tray plates in a plug-in mounting manner; a polariscope clamping slot is disposed at a front end of the polariscope tray; the metal curtain is a hard substrate or a flexible soft base cloth standing front of the hanger frame assembly; silver inks, sliver powders, reflecting powders, light stabilizers and the like are coated on the surface of the substrate or the base cloth to obtain a metal reflecting coating. The product has the advantages of simple structure, convenient splicing and mounting, good focusing effect of polariscope, good texture display performance of the curtain and the like.