Transient event detection is an important part of non-invasive load monitoring. However, the existing transient event detection methods need to know the active power jump amplitude of the load switching, and set the detection threshold of the power difference before and after the power jump, which makes it unable to be applied to multiple loads with different active power jump amplitude. Therefore, a transient event detection algorithm based on standard deviation multiple is proposed in this paper. The algorithm detects whether the change point occurs by the multiple of the deviation of active power from the mean value relative to the standard deviation, and accurately locates the change point by the time when the deviation multiple crosses the zero point most recently. The detection speed and accuracy of the deviation multiple method and sliding window algorithm are compared through simulation. The validity of the algorithm is verified by BLUED data set in the case of multiple load switching with different characteristics. Compared with the existing detection algorithms, this algorithm not only does not need to set the detection threshold of power difference before and after power jump, but also can be applied to the case of multiple load switching with different characteristics. The testing results show that the algorithm has better detection speed, detection accuracy, lower false detection rate and missing detection rate.