A device and method for controlling frame input and output are applied to the reception of image data from a source device and output of the image data to a destination device, the device includes a buffer, a buffer control circuit, and a frame write controller. The input pixel clock is not equal to the output pixel clock. The frame write controller generates a write permission signal according to the Input DE and the Output DE. The buffer control circuit generates a write control signal according to the Input DE and the write permission signal, and generates a read control signal according to the Output DE. The buffer receives the image data from the source device according to the write control signal and the input pixel clock, and outputs the image data to the destination device according to the read control signal and the output pixel clock.