Different empirical formulae in the calculation of the supercavity shape were analyzed, showing that the Guzevsky formulae has good precision and scope of application. Targeting on reducing the drag, enhancing the cavitation number and enlarging the volume of the supercavitating vehicle, an optimal design model of the conical supercavitator was built based on the Guzevsky formulae. The weight method and genetic algorithm were applied in solving the optimal problem. The results are consistent with the current theory. Effect of aspect ratios, cavitation numbers in the design process were studied. The results indicate that cavitation number is the most important factor that affects the dimension of the supercavity and the volume of the vehicle has been increased significantly through the optimal design process.