Due to the complexity of the cavity/vehicle and oscillation characteristics, streamlined shape integrated design of conventional fully wetted vehicles is not suitable for supercavitating vehicles. In this paper, a set of design criteria is highlighted to optimize the length and streamlined shape of a conical section subjected to realistic design constraints, which integrate the complex characteristics of the cavity/vehicle system under the condition of auto-oscillation of supercavitating vehicles. The auto-oscillation and its time-domain characteristics are determined. By deriving the equation describing (...) the cavity/vehicle relationship and identifying the maximum amplitude of the Euler angle, the cavity/vehicle tangent point criterion is proposed to determine the theoretical optimum value of the length of the conical section. A method of equal cross-sectional area for gas flow is proposed to design the streamlined shape of the conical section. Water tunnel and autonomous flight experiments were carried out to validate the feasibility of the design methodology developed in this work. (shrink)