Global atmospheric circulations are greatly affected by anthropogenic activities. Several atmospheric circulation models predict that the frequencies of extreme rainfall events and extreme droughts will increase in the future. Water is one of the most limiting resources for growth and development of plants in arid and semi-arid ecosystems. Furthermore, grassland ecosystems have been proven to be very sensitive to changing precipitation regimes. However, our understanding on the effects of extreme climatic events on the structure and functioning of grassland ecosystems is inadequate. By far, the definitions of extreme climatic events are still inconsistent. Therefore, based on analyses of the definitions of extreme climatic events and research methods in literature, we synthesize the effects of extreme rainfall events and extreme droughts on soil water and nutrient availability, individual plant development and physiological characteristics, community structure, ecosystem productivity and carbon cycling. In addition, we put forward five scientific questions on research concerning the impacts of extreme climatic events and identify two key issues on manipulative precipitation experiments to help with understanding the mechanisms on how grassland ecosystems respond to extreme climatic events in the context of global change.