Combined transmission of wind, solar and thermal power is an important type of new energy consumption. How to determine the capacity ratio is a difficult problem. The flexibility of energy storage regulation can smooth out the impact caused by the uncertainty of new energy output. However, frequent charging and discharging will reduce the service life of battery storage. A quantitative model of battery life is established based on the discharge depth and number of cycles of energy storage. A two-layer capacity optimization model of the wind-solar-thermo-storage-bundled power transmission system is established. The upper layer aims at minimizing the total cost of the system, and the lower layer aims at minimizing the typical daily scheduling cost. The influence of the uncertainty of new energy output on the system reserve capacity is treated by a chance constraint. The chance constraint is converted into a deterministic constraint by using sequence operation. The problem is converted into a mixed integer linear programming problem which is easy to solve. The results show that the energy storage configuration can effectively reduce system cost. At the same time, considering the energy storage service life, a more reasonable scheduling strategy can be formulated to help ensure economy, and the service life of the energy storage can be extended. This verifies the effectiveness of the model.