Abstract: In order to make use of the flexibility provided by the annual carbon compliance period and to produce decisions in the electricity and carbon spot markets that satisfy cash flow constraints, the daily decision problem of generation companies in the electricity and carbon spot market is studied. Firstly, a stochastic decision model of the electricity and carbon markets with cash flow constraints from a year-round perspective is established taking into account the billing cycles of different operation activities.Then, the number of decision variables is reduced by hybrid time-step modeling on the premise of describing the cash billing cycle,and the multi-stage stochastic optimization model is simplified into a two-stage stochastic optimization model for easy solution.Finally, the problem of frequent speculative trading in the second stage of the traditional two-stage model is solved by adding oneway trading rules in the decision model, and the problem of low expectation of future carbon purchase cost in the two-stage model is solved by adding timing trading rules. The case analysis shows that the proposed decision scheme effectively reduces the carbon purchase cost of generation companies and improves the overall income of the whole year, while ensuring the cash flow security.