The present invention relates to a stroke-restricting device of a linear actuator and a wire-reeling mechanism thereof. The linear actuator includes a base and a telescopic pipe. The stroke-restricting device includes a box, a movable member, a block, a pair of switches, and a wire-reeling mechanism. The box is fixed to the base and has a wall plate. The wall plate is provided with a through-hole. The movable member includes a rod penetrating the through-hole and movable with respect to the box. The block is fixed to the rod. The pair of switches is fixed to the box to correspond to the block. Each of the switches has a trigger portion for generating electrical signals by means of contact of the block. Each of the trigger portions is located at two opposite ends of a moving path of the block. The wire-reeling mechanism includes a wire disposed in the telescopic pipe and moving therewith. One end of the wire is connected to the movable member. By this structure, only a small space can be used to control a limit position of a long distance.