The invention relates to an electric shock fault moment detection method and device. The method comprises following steps of sampling in real time by utilizing a zero sequence current transformer, thus obtaining total leakage current sampling signals; selecting an ith sampling point from the total leakage current sampling signals as a reference signal; by taking the reference signal as a reference, selecting the total leakage current sampling signals of a former period; obtaining the skewness of the total leakage current sampling signals of the former period by utilizing a data window, wherein the skewness indicates the degree of asymmetry of the total leakage current sampling signals and the average value of the signals; and judging that an electric shock fault occurs if the skewness exceeds a skewness set value and outputting a tripping signal to a surplus current protective device at this moment. According to the method and the device, the organism electric shock fault moment can be identified from the total leakage current sampling signals rapidly, and therefore, the action sensitivity and reliability of the surplus current protective device can be improved.