Abstract: As a result of the sequential trading process, the decision-making of power purchasers is intercoupled across different trading periods. Therefore, power purchasers need to consider the trading risks in each period comprehensively and make power purchase decisions sequentially. However, the current power purchase strategies fail to consider the differences in the risks of power purchase costs across multiple trading periods, nor do they consider the intercoupling of multi-period power purchase decisions in the sequential trading process. To address this issue, this paper proposes an annual power purchase strategy considering the risks of multi-period sequential trading for power purchasers with a certain capacity for flexible regulation. Firstly, a set of multi-period scenarios is constructed, and the multi-period sequential trading risks are characterized based on the coupling relationships of multi-period sequential trading. Then, in accordance with the relevant provisions of the Shanxi electricity market, an annual electricity purchase decision-making model considering the risks of multi-period sequential trading is established. Finally, a case study is conducted to investigate the role of flexible resources in reducing electricity purchase costs and avoiding risks under the multi-period trading mechanism, as well as to analyze the impact of the scale of flexible resources on the allocation of electricity volume in each trading period.The results show that, compared with the strategy of allocating power volume among trading periods at a fixed ratio, the proposed strategy can reduce the annual power purchase cost by 1.65% and the annual power purchase risk by 1.41%.