The invention provides a voltage bilevel optimization droop control method for a distributed photovoltaic cluster, which belongs to the technical field of power system operation and control. The method includes steps of: establishing a distributed photovoltaic cluster droop curve optimization layer and a distributed photovoltaic local reactive power control layer respectively, two levels executingsimultaneously and separately, and the distributed photovoltaic cluster droop curve optimization layer periodically sending the optimization result to the distributed photovoltaic local reactive power control layer to enable the latter to adjust the reactive power output in real time according to the fluctuation of the system state, respond to the system's reactive power regulation requirements to the greatest extent, solve the contradiction between optimization calculation, cycle communication and real-time control, and reduce the photovoltaic off-net risk. The method fully utilizes the reactive power adjustment capability of distributed photovoltaic power generation nodes, reduces the calculation burden of the system, and reduces the operation and maintenance cost.