Abstract: In automatic aerodynamic optimization of blade shapes,the construction of design parameters of blade profiles needs to achieve that the number of the parameters is fewer but the blade profiles possess larger variability.In this paper,blade profiles are formed using blade mean camber lines and distribution of blade thickness along the camber lines.For construction of blade mean camber lines,the combination of a third order polynomial and a multi arc curve are used.The blade thickness is distributed by another third order polynomial.As examples,using above descriptive method,a low speed profile and a transonic blade profile can be satisfactorily reproduced.An automatic optimization algorithm is developed,in which the simplex method is adopted to search for optimal objective;the objective function value for aerodynamic optimization is calculated using the N S equation method.As an example,setting elimination of separation in the blade suction surface as an objective,the automatic optimization algorithm can achieve the objective satisfactorily.