A sychronized image transformation processing method for a printer is described for transformation of to-be-printed information into CMYK bitmap information, which may be actually printed by the printer, in which a rendering image process (RIP) device and a color matching and screening (CMS) device are provided for such image transformation. In this method, the RIP and CMS devices are operated synchronously by controlling resource and processing sequence of image segment buffers with software queues, so that a printer engine may rapidly receive the transformed CMYK bitmap information and thus print the to-be-printed information.