The embodiment of the invention provides a power control method, device and system of a wind power plant and computer equipment. The control method comprises the steps of obtaining running state dataof the wind power plant and a grid connection point in real time; according to the running state data, judging whether the state of the grid connection point satisfies conditions of secondary frequency modulation or not; if yes, according to the preobtained theoretical power value of the wind power plant, a given value of automatic power generation control and a standby active power value reservedfor primary frequency modulation, determining a limited power instruction value; according to the limited power instruction value, generating and sending an instruction used for controlling wind power generation unit active power of the wind power plant. By means of the power control method, device and system of the wind power plant and the computer equipment, on the basis that the wind power plant satisfies primary frequency modulation control, active power of secondary frequency modulation can be output, and coordinated control of the primary frequency modulation and the secondary frequencymodulation is achieved, so that the wind power plant has external characteristics of a quick frequency response.