Abstract: Previous researches on nitrogen nutrition of rice mainly focus more on ammonium (NH4+) than nitrate (NO3－). In fact, the roots of rice can excrete oxygen (O2) to surrounding soil and this can convert NH4+ to NO3－ in the process of nitrification at root surface or in rhizosphere. Therefore, rice roots are actually always exposed to a mixture of NH4+ and NO3－ even in flooded condition. This paper referred ecological significance of enhanced nitrate nutrition in rice and the nitrification process in the rhizosphere of rice, and then discusses the physiological and molecular mechanisms of enhanced nitrate nutrition in rice from root growth, nitrogen absorption and assimilation. Finally some issues on enhanced nitrate nutrition of rice are proposed to be further studied.