In this paper, the reliability of transmission line tower-line structure system under combined ice-wind condition is modeled and analyzed. Firstly, the reliability indices of pole-tower structure, insulator, fittings and grounding wire are calculated by checking point method of first-order second-moment method. Then, the reliability calculation method of series structure system is used to calculate pole-tower structure, insulator, fittings and grounding wire. Finally, taking a 220 kV straight tower and tension tower as examples, the system reliability indices of pole-tower structure, insulator, fittings and ground wire under combined ice-wind condition are calculated and analyzed, which can provide reference and guidance for disaster prevention of transmission lines.