It is of prevalent concern that rice paddy soil is one of the N2O sources to the atmosphere. Nitrification and denitrification are two microbial processes to produce N2O in soil. Water management is an important factor affecting N2O emission from rice paddy field. In this paper a review was presented to summarize the effect of water management during rice growing period and non-rice growing period on seasonal variations of N2O emission, pathways of N2O production, pathways of N2O emission, N2O-N emission factor and on nitrogen form or concentration and soil enzyme which are correlative to the process of N2O production and emission. This review also put forward the perspective for further study.