As distributed energy resources, flexible loads, and energy storage devices continue to grow, the distribution grid is gradually transforming into an active distribution network that actively participates in grid operation, regulation, and control. To address the inefficiency in utilizing energy storage devices and flexible loads, a coordinated optimization scheduling method for source, load and storage was proposed. Firstly, a multi-timescale scheduling model for active distribution networks was established. The objective functions were set to optimize the power quality and minimize the operating cost of the distribution grid, while considering constraints such as energy storage, network balance, and flexible load utilization. Finally, an active distribution network was constructed using the IEEE-33 system, and a multi-timescale scheduling strategy for day-ahead and intra-day operations was developed. A stochastic weighted particle swarm optimization algorithm was employed to solve the multi-objective optimization problem. The feasibility of the proposed method was validated.