Smart munitions had been developed for many years and had no uniform definition yet.In this paper we interpreted the definition of smart munitions with the integration of some main definitions on board and at home. Based on the definitions, smart munitions were classified and some typical ones were introduced including course correcting munitions, guided munitions, terminal sensoring munitions, wide area munitions and loitering munitions, which were used widely in battlefield in recent decades. Key technologies of these munitions were pointed out and furture development of the munitions were expected.