Abstract: Based on the blade element-momentum theory and a simple diffuser efficiency calculation method,this paper establishes a diffuser augmented wind turbine model for low wind speed scenarios. The model includes the correlation between the wind turbine incoming wind speed,impeller plane wind speed,diffuser outlet wind speed,wake wind speed,load of wind turbine blade,blade element parameters,and wind energy utilization coefficient. For a certain type of diffuser augmented wind turbine,the optimization design of blade structural parameters is carried out using this model,and the flow field of the wind turbine before and after the optimization design is simulated and verified using Fluent software. The analylsis results show that under rated operating conditions,the blade tip speed,impeller torque,and wind energy utilization coefficient of the diffuser augmented wind turbine before and after optimization design have been improved to a certain extent. The research results are expected to provide feasible directions for the blade design of small-sized low wind speed wind turbines.