Rapeseed is the world’s third largest oil crop,an important source of producing plant oil with highquality and feed protein,and has become one of the most valuable trade agricultural products. Rapeseed strictly requires water at each stage of growth and development. With the occurrence of global warming and heavy rainfall events,the environment of rapeseed production has deteriorated. The alternation of drought and flooding has a significant impact on the growth process and metabolic process of rapeseed,and ultimately reduces the yield and quality of rapeseed. “One sowing and all seedlings” is the basis for the high and stable yield of crops. The water condition of rapeseed after sowing largely determines the number of seedlings. The effect of water condition at each stage of growth and development after seedlings on rapeseed production cannot be underestimated,which determines the final production benefit of rapeseed. Under water stress,the drought (flooding) signal is first sensed by the root system of rapeseed. At the same time,a series of physiological reactions including stoma closure,weakening of photosynthesis and osmotic adjustment occur in the aboveground part of the plant. The aboveground and underground parts of plant simultaneously activate corresponding mechanisms to resist water stress. However,studies about indepth analyses of the rootshoot interaction of rapeseed are rare.