A method for detecting an available active power of a wind turbine, comprising: acquiring (S110) a current rotation speed of a rotor of a wind power generator of a wind turbine and a current outputted active power of the wind turbine; determining (S210) a current tip speed ratio of the wind turbine, based on the current rotation speed and the current outputted active power; determining (S120, S220) an effective wind speed of the wind turbine, based on the current tip speed ratio and the current rotation speed; determining (S130) a maximum active power capable to be captured by the wind turbine at the current rotation speed, based on the effective wind speed and a maximum utilization-rate coefficient for wind energy of the wind turbine, wherein the maximum utilization-rate coefficient for wind energy is a largest one among a plurality of utilization-rate coefficients for wind energy corresponding to a plurality of pitch angles under the current tip speed ratio; determining (S140) a maximum active power capable to be outputted by the wind turbine, based on the maximum active power capable to be captured and a corresponding power loss, and determining a release power, at which the wind turbine is capable to release rotation kinetic energy of the wind turbine for a predetermined time at the current rotation speed, wherein the release power is boosted power during primary frequency regulation of the wind turbine; calculating a sum of the maximum active power capable to be outputted and the release power; and obtaining the available active power of the wind turbine by subtracting the current outputted active power from the sum. acquiring (S110) a current rotation speed of a rotor of a wind power generator of a wind turbine and a current outputted active power of the wind turbine; determining (S210) a current tip speed ratio of the wind turbine, based on the current rotation speed and the current outputted active power; determining (S120, S220) an effective wind speed of the wind turbine, based on the current tip speed ratio and the current rotation speed; determining (S130) a maximum active power capable to be captured by the wind turbine at the current rotation speed, based on the effective wind speed and a maximum utilization-rate coefficient for wind energy of the wind turbine, wherein the maximum utilization-rate coefficient for wind energy is a largest one among a plurality of utilization-rate coefficients for wind energy corresponding to a plurality of pitch angles under the current tip speed ratio; determining (S140) a maximum active power capable to be outputted by the wind turbine, based on the maximum active power capable to be captured and a corresponding power loss, and determining a release power, at which the wind turbine is capable to release rotation kinetic energy of the wind turbine for a predetermined time at the current rotation speed, wherein the release power is boosted power during primary frequency regulation of the wind turbine; calculating a sum of the maximum active power capable to be outputted and the release power; and obtaining the available active power of the wind turbine by subtracting the current outputted active power from the sum. <EOS>