The invention relates to a method for cooperatively controlling active power of a wind farm, comprising the following steps of: obtaining an excess value of active power fluctuation and taking the excess value and a power excess trend as the input and output excess deviation values of a logic controller; then taking the difference between the excess value and a power frequency deviation value as the input of a PI controller; and finally outputting an active reference value of a motor of a wind farm. In the method, the maximum wind power utilization of a single machine is unlinked by utilizinga control method and inserted into the integral cooperative control of the wind farm, so that the wind turbine has an adjustable allowance, and load fluctuation of a power grid caused by unstable wine energy is balanced to the greatest extent; the balancing can release more space of the power grid, and the effective load transmitting capability is improved. Because active power modulation calculation is based on wind energy prediction, the self protection of the wind turbine is changed from a passive propeller regulation or splitting type into an active prevention type, the operation efficiency of the wind turbine is effectively improved, the impact of the power grid is reduced, and the operation of the wind turbine is protected.