Abstract: To study the influence of soil nutrient level on plasticity of floral characteristics in Iris japonica Thunb.,The experiment was carried out under high,medium,low levels of N,P,K.The experiment indicated that the length and width of outer petal,inner petal,the pistil and stamen length and the corolla diameter increased with the increase of soil nutrient level.Correlation between every two components of the flower was significant at 0.05 level.The results were discussed in the context of adaptation of plants to environmental heterogeneity.