Abstract: Driven by the global energy structure transformation and the "dual carbon" goal, the wind power industry urgently needs to shift from large-scale expansion to refined operation. This article first compares five blade tip configurations, including elliptical blade tip, straight blade, added end plate, suction surface mounted small wing, and pressure surface mounted small wing, to determine the engineering application value of blade tip small wing in increasing power and efficiency of old wind turbines. Subsequently, this article selected a mountainous wind farm in Shaanxi to conduct empirical design, using the aerodynamic structural collaborative optimization method to determine the core parameters of 1500mm extension length and 119° winglet angle. The technical transformation results show that in the wind speed range of 3~10 m/s, the power gain rate of the unit reaches 1.4%~59.9%, with a power increase of over 14% in the low wind speed zone (3~5 m/s); the annual equivalent power generation (AEP) has increased by 3.5%~10.8%, the fluctuation amplitude of basic load has decreased by 85%, and the convergence of dynamic response under extreme working conditions has significantly improved. Economic analysis shows that the cost of single machine renovation is 650000 yuan, and the static recovery cycle is only 2.7 years. This study provides a technically feasible and economically competitive solution for increasing the power and efficiency of existing assets in wind farms.