Abstract: Due to the uneven and uncertain distribution of runoff in time and space, hydropower is greatly different from the electricity market dominated by thermal power. Therefore, how to evaluate the risks of cascade hydropower in power trading is an urgent problem to be solved. In this paper, the risk analysis method of cascade hydropower station participating in the market transaction coupled with monthly transaction and day-ahead incremental transaction was constructed by combining the power market transaction rules of a hydropower station in Southwest China, which plays a leading role: Copula-Monte Carlo was used to generate the combined scenario of daily runoff and clearing price, and the enhanced elite retention strategy genetic algorithm was used to calculate the generation income of all scenarios, and the corresponding conditional value-at-risk value (CVaR) was obtained according to the confidence level. The proposed method takes into account the uncertainty of runoff and electricity price, as well as the settlement order and deviation assessment of each transaction in the settlement rules, and can directly solve the return and risk value. The process is simple and the physical meaning is clear. Taking the actual data of a grid cascade hydropower participating in the electricity market as an example, the results of the simulation analysis show that the proposed method can easily solve the transaction portfolio risk value, and can more reasonably evaluate the return risk value compared with the single consideration of electricity price and runoff.