The invention provides a distributed photovoltaic maximum permeability determination method and device. The method comprises the following steps: circularly executing the following steps until the difference value between the load prediction stability of a target area and the preset load prediction stability is within a preset range, and determining the latest distributed photovoltaic permeabilityas the distributed photovoltaic maximum permeability: obtaining actual load data under the set distributed photovoltaic permeability; obtaining a low-frequency component and a high-frequency component of the sequence of the actual load data under the set distributed photovoltaic permeability; obtaining the load prediction stability of the target area; and if the difference between the load prediction stability of the target area and the preset load prediction stability is not within the preset range, adjusting and setting the distributed photovoltaic permeability, and replacing the adjusted distributed photovoltaic permeability with the set distributed photovoltaic permeability. According to the method, the distributed photovoltaic maximum permeability can be determined, the load prediction stability is considered, and load prediction and power balance arrangement can be effectively supported.