Ammonia Absorption by plant canopy is recognized as an important part of NH3 exchange between plant canopy and atmosphere. The research advance of NH3 absorbed by plant canopy was reviewed in this paper, mainly including the methods for determining ammonia absorption, the mechanism of ammonia absorption and the influencing factors as well as the influences of increasing NH3 concentration in atmosphere on plant nitrogen cycle. Problems need to be solved of ammonia absorption in future research were discussed and the latest research results of foliar uptake of volatilized ammonia after fertilization by rice were also presented in this paper.