In this paper, a new method of current transformer saturation detection based on Savitzky-Golay (S-G) filter is proposed. The method combines the traditional difference equation and the S-G filter, and can accurately detect the saturation point of the current transformer in the condition of low signal noise ratio. On the basis of current transformer saturation start time, the current integration method can be used to accurately detect the end of current transformer saturation. The threshold value of the differential equation method combined with the S-G filter is derived, and the new method is simulated by PSCAD/EMTDC. The simulation results show that the current transformer saturation detection method based on S-G filter has the advantages of simple algorithm, high detection precision, strong anti-interference ability and so on.