Abstract: Wind energy is an important part of renewable energy and support for realizing the goal of "double carbon".It’s urgent to upgrade the wind turbines in the old wind farms because of the old equipments and heavy costs of the operation and maintenance. Thus taking the example of the equal capacity transformation of "replacing small with large" in a Ningxia wind farm, based on the analysis of the wind and land resources, the transformation schemes were compared and selected from the aspects of technology and ecomomy. The original 108 sets of 850 kW wind turbines were arranged into 9 sets of 5.0 MW and 9 sets of 5.2 MW units to realize the economical use of land resources and increase the efficiency of wind resources, and to leave some room for the later increase of wind turbine capacity. The transformation results show that the utilization hours of power generation can be increased to 2 710 h after the transformation, which is 2.45 times higher than the same period of the previous year. The selection of the scheme can provide a certain reference for the implementation of similar projects in the future.