The invention relates to a power distribution network overvoltage suppression method and system based on an active power limit value algorithm. The method comprises the steps as follows: when the voltage value of a key busbar of a photovoltaic system of a power distribution network exceeds a power distribution network overvoltage alarm value, active power limit values of the key busbar and commonbusbars are determined according to the overvoltage alarm moment of the power distribution network as well as active output values and voltage values of the key busbar and the common busbars of the photovoltaic power generation system of the power distribution network at the current moment, the power extraction capacity of each busbar in the photovoltaic power generation system is determined according to the active power limit value of the key busbar and the active power limit values of common busbars, and suppression of overvoltage of the power distribution network is realized according to the power extraction capacity of each busbar. According to the technical scheme, active output of the photovoltaic system is limited and regulated, the occurrence rate that the voltage is out of limit is effectively suppressed, the problem of high costs of the prior art is solved, and overvoltage suppression of the power distribution network is realized precisely on the premise of simple configuration.