The invention belongs to the technical field of power machines and relates to a device for converting gravity into power. According to existing mechanical design using gravity for acting, the power conversion performance is relatively poor, design is complex, the size is large, and cost is high. In order to solve the problems, the device for converting gravity into power is provided, wherein the gravity center of the human body is changed to act on a pedal (1), the two ends of the pedal (1) move up and down like a seesaw, and gravity is converted into power through a power conversion box (4). The device has the beneficial effects that no matter which end of the pedal applies force downwards, the force can be converted into power through the power conversion box (4), the power is rotationally output in one direction all the time through a gear (2.10), the size is small, the structure is simple, the weight is small, cost is low, power is converted efficiently, the device can be widely applied to machines such as a small boat, a trolley, a sliding plate (or a scooter) and a surfboard, practicality is high, the device which is brand new, simple in structure, high in efficiency, capable of saving labor, convenient to use, practical and simple in power conversion is provided for the machines, and the life quality of people is improved.