A print device with a surface identifying function includes a feed roller assembly; a print assembly; an obtaining module; a determining module; a control module; a sliding control module; at least one sliding bar and a printed surface identifying assembly. The sliding control module controls the printed surface identifying assembly to slide along the sliding bar. The obtaining module controls the printed surface identifying assembly to identify if one or both surfaces of the sheet of paper have already been printed, and generates a result. The determining module determines whether the paper is available for printing according to the result. The control module controls the print assembly not to perform the printing task and the feed roller assembly to take the paper out of the print device when the paper is unavailable for printing. A printing method is also provided.