The invention discloses a cascade reservoir group short-term optimization scheduling method and system, and belongs to the field of hydro-thermal power station collaborative optimization scheduling, and the method comprises the steps: obtaining the fitness of each individual in an initial population, and updating the positions of an optimal fitness individual, a suboptimal fitness individual and athird optimal fitness individual in the population; updating the positions of all individuals in the population, and generating a temporary population; screening populations by adopting a mutation strategy based on the populations and temporary populations obtained after updating all individual positions of the populations; and an adaptive boundary strategy is adopted to effectively prevent the population from falling into local optimum; and updating all individual positions in the population through iteration, and outputting the optimal fitness individual position as the optimal scheduling process of the cascade hydropower system after a stop condition is reached. The invention has the advantages of being high in convergence speed, high in solving precision, high in optimizing capacity,capable of effectively avoiding falling into a local optimal solution and the like, can well coordinate cooperative scheduling of the water-heat power stations between the power grids, improves economic benefits and has high practical value.