A display method comprises a first device projecting a first window interface to a second device after receiving a screen projection instruction entered by a user. The first device receives an instruction for running a second window interface, and may send a task identity of the second window interface and a security protection instruction to the second device after determining that the second window interface includes a security flag bit. Further, the second device displays the first window interface and a security interface, where the security interface is a projected interface of the second window interface.