The influence of different N forms i.e. (NH4)2SO4, NH4NO3 and Ca(NO3)2 on plant growth, enzymatic activities, nutrient concentration, yield components, root exudation and Cd and N accumulation of rice plants exposed to different cadmium levels (0, 1 and 5 μM)were studied in a hydroponics experiment. The result shows that the effect of Cd on all measured parameters were N source and plant organ dependent. However, the reduction in all plant growth parameters, including photosynthetic rate, chlorophyll content and fluorescence efficiency became more predominant with the prolonged stress exposure and increased Cd level. There was no significant difference in all these parameters among three N forms when no Cd was added into the culture solution. While for the plants exposed to Cd stress (1 and 5 μM), the difference was significant among the three N forms. The least inhibition in growth parameters was recorded in (NH4)2SO4-fed plants and the greatest in Ca(NO3)2-fed plants. Cd stress significantly reduced NR activity and the extent of reduction was N forms dependent, with greatest reduction in Ca(NO3)2-fed plants and least in (NH4)2SO4-fed plants. Furthermore, a significant difference was also noted among the three N forms in Cd and N concentrations and accumulation under Cd stress, with (NI-I4)2SO4plants having less Cd uptake and more N accumulation. Addition of 1 μM Cd has shown a significant increase in POD and CAT activities and gultathione content, with greatest POD and CAT activities and lowest glutathione content in Ca(NO3)2-fed plants and vise versa in (NH4)2SO4-fed plant. The highest quantity of malic acid was noted in (NH4)2SO4,-fed plant while the maximum citric, oxalic and acitic release was observed in Ca(NO3)2-fed plants when Cd was added to solution. In comparison with the control plants, the decrease in root and shoot S, P and K content of Cd-treated plants were not obvious in (NH4)2SO4 treated plant, but the decrease was significant in Ca(NO3)2-fed plants. Moreover, under Cd-stress the maximum yield and highest N and lowest Cd (root, shoot and grain) contents were also recorded in (NH4)2SO4,-treated plants. The differences in enzymatic activities, root exudation, nutrient concentration, root, shoot and grain N and Cd uptake of rice plants among different N forms indicated (NH4)2SO4 as a reasonable fertilizer from in Cd contaminated paddy fields.