The invention discloses a single-phase earth fault distinguishing method and a single-phase earth fault distinguishing device based on an SVM (support vector machine). The method comprises the following steps of continuously acquiring zero-sequence voltage current data of a line; acquiring zero-sequence voltage current data of a sudden change moment, a cycle before the sudden change moment and a cycle after the sudden change moment in response to the sudden change of the zero-sequence voltage current of the line, and calculating a deviation value of each of the zero-sequence voltage and the zero-sequence current; calculating fault membership values based on the zero sequence voltage current deviation values; and serving the fault membership value and the moment/moment information thereofas the input of a support vector machine classifier obtained by pre-training in response to the condition that any one of the fault membership values corresponding to the sudden change moment, a cyclebefore the sudden change moment and a cycle after the sudden change moment is not zero, and then judging whether the single-phase ground fault occurs or not according to the output of the support vector machine classifier. Through the method disclosed by the invention, the single-phase earth fault of the system can be judged, and the judgment result is accurate and reliable.