The invention provides a method for authenticating a smartphone user based on multi-image switching. The method comprises the steps of firstly, selecting an image sequence by the user, then, recording a motion feature sequence of fingers when the user switches images, wherein the image sequence is stored in an internal storage of a smartphone, and the motion feature sequence comprises starting point coordinates, end point coordinates, speed and the like. The feature sequence is processed and then marked as feature codes of the user, wherein the feature codes are used for distinguishing different users. Compared with PIN authentication, the method has the advantages of greatly expanding secrete key space, being convenient to use, practical and free of adding any additional device, and having the quite high recognition rate and safety.