Type 31 may refer to:
Type 31 frigate, a class of Frigate currently being built for the Royal Navy Type 31 75 mm mountain gun, a field gun of the Imperial Japanese Army a version of the M2 mortar produced in the Republic of China Type 31 Grampus I, a variant of the Bristol Grampus, an early British prototype aircraft Villiers 31, an early French passenger aircraft Tupolev Tu-85, a Soviet prototype aircraft, designated as Type 31 by the US Air Force Hispano-Suiza Type 31, an early Spanish aircraft engine Peugeot Type 31, an early French motor vehicle an early Datsun motor vehicle Type 31 Alphabetical Duplicating Punch, an IBM keypunch