Abstract: In view of the challenges caused by the resource characteristics of hydropower "surplus during wet seasons and shortage during dry seasons" to the power system peak regulation and the transmission channel utilization, a coordinated two-layer optimization of gas-hydropower considering the bundling of gas-hydropower outbound transmission is proposed. Firstly, analyzing the development mode of the gas-hydropower integration in Sichuan and Chongqing areas, this paper proposes a gas-hydropower bundling and outward transmission mode. Secondly, a two-layer optimization model of coordinated gas-hydro power generation considering the gas-hydro power bundling out is established. The upper level model takes as its objective function the maximum of the total annual profit of the system taking into account the investment costs of the gas-fired power stations, achieving the optimal capacity allocation for gas-hydro coordination. The lower level model uses the maximum of the annual operating revenue as the objective function to achieve the coordinated and optimised gas-hydro operation. Then, the chaotic particle swarm optimization algorithm combined with the CPLEX solver is used to solve the model. The Shapley value method is used to achieve the profit sharing for the gas-hydro power bundling out. Finally, an arithmetical analysis of a certain regional power system is presented as an example. The results show that the proposed model is able to optimally allocate the installed capacity of the gas-fired power stations, achieve the coordinated and optimal operation of gas and water, alleviate the peaking dilemma caused by the seasonal contradiction of hydropower, and improve the utilisation rate of the outward transmission channel.