A support mechanism includes a bracket, a sliding member, a connecting unit, and an elastic member. The sliding member is slidably connected to the bracket. The connecting unit includes a first arm, a second arm pivotally connected to the first arm, a first pivot pivotally connecting a first ends of the first arm and the second arm, a second pivot pivotally connecting a second end of the first arm opposite to the first pivot and the bracket, a third pivot pivotally connecting a second end of the second arm opposite to the first pivot and the bracket, and a connecting piece sleeved on the first pivot. The elastic member is positioned between the connecting piece and the bracket. The sliding member resists the first arm and the second arm by an elastic force of the elastic member acting on the first arm and the second arm.