The invention discloses a dynamic windproof device of a rail-mounted crane, which comprises a monitoring component, a trigger component, a power transfer component and a buffer component. The monitoring component is connected with the trigger component, the trigger component is arranged on a crane trolley, the buffer component is arranged on a lower cross beam of the crane and a cart anchorage device, and the power transfer component is connected with the trigger component and the buffer component. Through the components, under abrupt gust, the crane is blown to a definite speed and the gust continuously accelerates; under the condition that the prior windproof device such as a metal shoe rail clamping device and the like cannot act, the dynamic windproof device realizes safe and steady braking of the crane; self wheel pressure of wheels of the crane trolley provides positive pressure, the rolling is changed into sliding, and a friction material is added, so the friction coefficient of contact faces is improved, the energy is saved, and the windproof grade is improved; and the buffer component of the invention makes the braking mild under the action of wind of different grades, ensures that the mechanical property of each component can be fully exerted, improves the windproof reliability, and ensures stability.