In order to improve the self-starting performance and wind energy efficiency of a wind turbine with a drag rotor, a twisted blade with a torsion angle of 90° was constructed. Based on the unsteady reynolds mean N-S model and k-ω SST turbulence model, the process from self-starting to steady-state operation of the twisted blade was numerically simulated, and the influence of the characteristics of the wind turbine near-flow field on the rotor performance was evaluated. The results show that the twisted blades with torsion angle of 90° can adapt to different flow directions. This kind of airfoil not only improves the applicability of different environments, but also improves the self-starting ability. At the same time, the distorted airfoil can effectively prevent the fluid from escaping from the concave tip of the forward blade and the return blade, which is beneficial to maintain the pressure difference between the concave and convex sides of the blade and correspondingly increase the energy conversion. Eddy currents were found at the tail of both the reflux blade and the forward blade, and such periodic eddy shedding could easily lead to the oscillation of the rotor structure and induce the fatigue failure of the structure. The research results can provide useful help for the development of resistance rotor fans with torsional blades.