An energy supply method and device for a monitoring wireless sensor node of a roller. A node energy supply device (2) is arranged on a roller web (1). The node energy supply device (2) comprises a generator (2-1), a disc rail (2-3), an input shaft (2-4), a swing link (2-5), a swing wheel (2-8) and an energy collection module (2-10). The generator (2-1) is driven to rotate using the rotation motion of the roller, the mechanical energy is converted into electric energy by the generator (2-1), and power is supplied to a monitoring wireless sensor node by the energy collection module (2-10). After rectification, filtering and voltage stabilization are conducted on the electric energy generated by cutting a magnetic induction line when the generator (2-1) operates, the energy collection module (2-10) uses the electric energy for charging an internal battery of the monitoring wireless sensor node. When the roller operates, the swing wheel (2-8) will keep vertically downward because of the gravity action thereof, thereby rotating relative to the input shaft (2-4) of the generator (2-1) to drive the generator (2-1) to operate. The present invention has the advantages of simple structure without manual operations, and energy saving and environmental protection.