The embodiment of the invention provides a detection method, device and equipment for power grid voltage frequency. A voltage sampling signal sequence is obtained through sampling the voltage signalsaccording to a preset sampling frequency; a first signal sequence and a second signal sequence are obtained based on the voltage sampling signal sequence, wherein the first signal sequence and the second signal sequence respectively comprise voltage signal values based on the voltage sampling signal sequence at each sampling point, and a first signal value and a second signal value are obtained through summation according to a preset calculation rule; the voltage signal frequency can be determined based on the preset sampling frequency, the window duration of the first time window, the first signal sequence and the second signal sequence used in the preset calculation rule. The invention is advantageous in that in the process of detecting the frequency of the voltage signal, only the sampling values of the voltage signals subjected to sampling of the voltage signals need to be used for carrying out summation operation, and the frequency of the voltage signals can be obtained without complex trigonometric function operation, so that the calculation amount is small, the detection speed is fast, and hardware implementation is easy.