A scanning apparatus adaptable for two resolutions has two carriages with different resolutions. The carriages are disposed in the cover and the scanning bed of the scanning apparatus respectively. Each carriage includes a lens and a sensing module and the sensing module and the lens are at a fixed distance. The optical lengths between the lenses and the documents to be scanned are different so that the resolution produced by the carriage in the cover is different from the resolution produced by the carriage in the scanning bed.