A hand-detecting brake system for baby stroller is equipped on a stroller frame, including a handle holder, a brake mechanism, an electric motor, and a battery. The handle holder is connected to one end of the stroller frame equipped with a hand-detecting device for creating a signal when user's hand being held or touched on the handle holder. The brake mechanism is operatively mounted on one side of a first wheel of the stroller frame for braking and un-braking the first wheel. The electric motor is capable of driving the brake mechanism to brake the first wheel when being received the signal from the hand-detecting device, and un-brake the first wheel when the signal from the hand-detecting device being disappeared. The battery electrically connected to the hand-detecting device and the electric motor for supplying needed power thereto.