Abstract: Taking offshore wind energy project as investigation object, the aerodynamic performance and geometric characteristics of wind turbine rotors with large capacity (1 MW to 10 MW) were analyzed in connection with their main characteristic parameters (e. g. rated wind speed, blade tip speed, and rotor solidity). First, it was pointed out that an essential criterion of high-performance wind turbine is its annual usable energy pattern factor, which should be as high as possible with its dimension possibly minimum as well, so that a maxmium wind energy would be captured and maxim al annual power output obtained. Then the in fluence of above-mentioned three parameters on the pattern factor and rotor geometry of wind turbine operated in Chinese offshore meteorological environment was investigated. The variation pattern of aerodynamic and geometric parameters were obtained, analyzed, and compared with each other. Finally, it was pointed out that the method for aerodynamic analysis and its result could be taken as a basis for evaluation of aerodynamic performance of large-scale offshore wind turbine rotors.