The invention provides a wind turbine generator power property evaluation method which comprises the following steps: verifying wind turbine generator main control operation data, modifying cabin air speed data, and calculating a wind turbine generator power curve and a power curve guarantee value, thereby obtaining a wind turbine generator power property evaluation result. By adopting the method provided by the invention, the wind turbine generator power curve is economically and efficiently evaluated, conventional wind turbine generator main control system operation data is sufficiently utilized, and power properties of all wind turbine generators of a same model in a wind power plant can be evaluated; both the accuracy and the testing efficiency can be ensured, the testing time is controlled within one month, and furthermore reliable operation and efficient utilization of the wind turbine generators can be ensured.