The utility model provides an undercarriage guard flap relates to aircraft structural design field, include: guard flap (1) and linking bridge (2). Guard flap (1) is close to the one side of nose -gear tire (4) and adopts two curved surface design, and through the mode of dredging, the fragment who splashes aircraft tire deflects to the wheel outside, also can not impact aircraft belly equipment even bounce once more behind the fragment striking ground, and establish guard flap (1) in the dead astern of nose -gear tire (4) through linking bridge (2), the fragment that nose -gear tire (4) splash can be blocked by guard flap (1) completely, the utility model discloses an undercarriage guard flap, the volume is less, weight is lighter, conveniently takes in the undercarriage cabin, the installation is succinct, and convenient all kinds of aircrafts use.