A regional power grid reactive power and voltage optimization model based on a new energy output timing segmentation strategy is proposed to address the issues of relatively large active power loss and voltage fluctuation in regional power grids and high reactive power cost and environmental cost caused by high-proportion new energy integration. Firstly, a new energy output segmentation strategy is established according to the timing characteristics of new energy output. That is, the top-down algorithm is used for segmentation processing with the goal of maximizing the dispersion between average values of new energy output in each time period and minimizing the dispersion within each time period. Secondly, introducing a reactive power pricing model, an optimization model for regional power grids with multiple energy sources such as wind, solar, thermal, and storage is established with the goal of minimizing the sum of standardized active power loss, node voltage deviation, reactive power source cost, and environmental cost of thermal power units in each time period. The improved firefly algorithm (IFA) is used to calculate the new model. Finally, the IEEE 30-bus system is used to verify the validity of the model. The results show that the proposed optimization model can effectively reduce the active power loss, reactive power source output cost, and environmental cost of the system, reasonably allocate reactive power of the power grid, and improve the voltage quality of the system.