The invention discloses a bridge flange anti-collision wall repair support and a mounting method thereof. The bridge flange anti-collision wall repair support comprises a fixing support and a groutingsupport, the fixing support comprises a horizontal frame and a vertical frame, a first adjusting component is arranged at the top of the grouting support, a second adjusting component is arranged onthe vertical frame, the grouting support is connected with the horizontal frame through the first adjusting component, a grouting tank is arranged at the bottom of the grouting support, the first adjusting component is used for adjusting a vertical position of the grouting support to put the grouting tank to a to-be-repaired position on the undersurface of an anti-collision wall, and the second adjusting component is used for adjusting a horizontal position of the grouting support to enable the grouting support to closely fit on the outer wall of the anti-collision wall. The undersurface of the anti-collision wall is grouted and repaired through the fixing support and the grouting support, and position of the grouting tank is adjusted through the first adjusting component and the second adjusting component to enable the grouting tank to be closely fitted with the to-be-repaired position. The bridge flange anti-collision wall repair support is simple in structure and convenient and quick to mount and demount, and construction difficulty is lowered greatly.