To reduce the mass of tensegrity structure, this paper provides a minimal-mass optimization method and self-similar iterative design method for further reducing the mass. Taking a cylindrical tensegrity structure as the research object which is under the action of external load, and based on the relationship of component quality and the material failure mode, the force density and cross-section area are used to minimize the structural mass subjected to an equilibrium condition, and the answer is provided by a linear program. In this process, the selection method of minimal mass is provided under two failure modes, compression bar buckling and yield. For further reducing the quality, 3D T bar self-similar iterative structure is applied to the cylindrical tensegrity structurea, and a self-similar iterative design method to design a lighter tensegrity structure is proposed, in which the conception of effective alternative space is presented and a method is given for calculating the effective space. Examples show that the minimum quality optimization method and the design method of self-similar iteration can design a lighter tensegrity structure.