The utility model discloses a cross-flow fan side plate which comprises a bottom plate, mounting plates are symmetrically arranged on the two sides of the bottom plate, a connecting plate is arranged between the mounting plates, a groove-shaped plate is arranged on the side, away from the connecting plate, of each mounting plate, and a wind wheel mounting cavity is formed among the bottom plate, the connecting plate and the groove-shaped plate. A mounting hole is formed in the middle of the mounting plate, a plurality of receding notches are sequentially formed in the mounting plate along the circumference of the mounting hole, a wind wheel mounting cavity can be formed by the bottom plate, the connecting plate and the groove-shaped plate, and the three plates serve as protection plates for protecting a wind wheel; the wind wheel is prevented from colliding with other objects during disassembly, the wind wheel is prevented from becoming present, and normal work of the wind wheel is affected, meanwhile, the mounting plates at the two ends of the fan side plate are square plates, the mounting area of driving motor parts can be increased, mounting holes and a plurality of receding notches are formed in the mounting plates, and the driving motor parts can be further conveniently mounted.