A method and a device for generating a three-dimensional image are provided. In the method, in an Nth time slot, an Nth left-eye image is received and stored in a download buffer of a first memory unit by a first control unit. An Nth right-eye image is received and stored in a download buffer of a second memory unit by a second control unit, where N is a positive integer from 1 to M, and M is a positive integer. In an (N+1)th time slot, the Nth right-eye image is received from the second control unit through a data transmission interface and stored in a receive buffer of the first memory unit. In an (N+2)th time slot, the Nth left-eye image and the Nth right-eye image are combined into an Nth three-dimensional image stored in a display buffer of the first memory unit for real time display.