Folding wing deployment scheme of small patrol UAV has an important influence on UAV flight mode switching. According to folding characteristics and deployment requirements of UAV folding wing， two deployment schemes synchronous deployment and stepwise deployment are proposed. With deployment dynamics model of a folding wing being established based on Lagrangian method， and folding wing drag force during deployment being calculated with aerodynamic simulation tool， driving torques needed for different deployment schemes are obtained. Driving torque is used as the evaluation criterion to optimise deployment scheme of the folding wing. Simulation results show that the stepwise deployment scheme has a short deployment time and a small deployment torque to reach the required deployment position. Finally， a deployment mechanism is designed for the stepwise deployment scheme， and static strength analysis of the structure is provided to verify the feasibility of the structure.