The cable-strut structure optimisation of a large space cable-strut tensioned parabolic cylindrical antenna is studied. Firstly, the deployment mechanism is designed, and the degree of freedom and kinematics analysis of the mechanism are conducted. Secondly, a complete tension cable configuration with 58 tension cables in 24 categories is established on the basis of the structural characteristics and constraints. A configuration optimisation design method based on the influence coefficient of comprehensive stiffness is proposed. A less tensioned cable optimisation configuration with better static and dynamic stiffness performance is established on the basis of the fully tensioned cable configuration and using the proposed method, and the stiffness characteristics of the configuration are verified through the analysis of an example. Lastly, a mathematical surrogate model between the designed angle and length parameters of the reflector rod system and the fundamental frequency of the antenna is established using the response surface method, and the optimal solution of the reflector rod system is obtained by a genetic algorithm. The effectiveness of the optimisation is verified by finite element modelling and simulation analysis. This study provides a basis and reference for the structural dynamic modelling, characteristic analysis and optimal design of a large space cable-strut tensioned parabolic cylindrical antenna.