A method of customizing the startup logo of a projector. The main steps of the method include the following. First, a projector is connected to an external device. Thereafter, in batches, image data is read from an image file in the external device, stored in a memory buffer and written into a built-in flash memory of the projector to replace the startup logo with the image file. The method has the advantage of reaching the maximum resolution supported by the projector without any scaling operation or losing any quality. Moreover, the startup logo is fetched from an external device. Hence, its source is more comprehensive and can be changed at any time.