The invention provides an active power control method and device for a photovoltaic power station. The method comprises the steps of judging an active instruction according to the current active powervalue acquired in advance, calculating the difference value between the instruction power and the current active power, judging the relation between the difference value and the power control dead zone, checking the active instruction according to the active control locking working condition, checking whether the active instruction is in the active power output range of the photovoltaic power station or not, assigning the active instruction according to the difference value and the adjusting dead zone, an active control locking condition, and the judgment result of the active instruction andan active power output range. The device comprises an instruction judging module, an instruction checking module and an instruction assigning module. According to the technical scheme, the photovoltaic inverter can work preferentially in the maximum efficiency interval in the active power control process, so that the inverter keeps higher power conversion rate, and the output efficiency of the whole power of the photovoltaic power station is improved.