In order to deal with the challenges brought by the uncertainty of renewable energy supply to the medium and long-term contract performance of new energy power generation enterprises, this paper puts forward a method to determine the medium and long-term contract electricity between new energy power generation enterprises and independent energy storage. Based on the opportunity constraints of new energy generation and the performance constraints of independent energy storage, a model for determining the medium - and long-term contract capacity between new energy generation enterprises and independent energy storage is constructed with the goal of the common benefits of power generation enterprises and independent energy storage. By introducing conditional value at risk (CVaR) and alternative variables, the model is reformulated as a mixed integer programming (MIP) model for easy solution. An example is given to analyze the monthly contract power decomposition curve of new energy power generation enterprises, and the validity of the proposed method is verified. At the same time, considering the influence of new energy power generation enterprises" risk preference and energy storage charging state on common benefits, the research shows that the energy storage charging state is negatively correlated with common benefits, and improving the risk preference of new energy power generation enterprises can improve the expected benefits of the contract community.