A method includes running, in an always-on display state of the mobile device, a first algorithm program to display a first clock interface in a first display area of a display of the mobile device, receiving a switching instruction when the mobile device is switched from a first clock style to a second clock style, wherein the second clock interface is different from the first clock interface, performing switching from the first algorithm program to a second algorithm program in response to the switching instruction, and running, in the always-on display state, the second algorithm program to display the second clock interface in a second display area of the display, wherein a size of the second display area is different from a size of the first display area, and wherein the second algorithm program is different from the first algorithm program.