Abstract: The influences on respiratory intensity, cytochrome oxidase activity and respiratory pathway in roots of rice seedings were investigated under various concentrations of nitrogen and phosphorus in mimic wastewater, When the rice seedlings were treated by mimic wastewater containning lower Nand P, the respiration rate, respiratory quotient and cytochrome oxidase activity increased in direct ratio with Nand Pconcentrations, However, they decreased when Nand Pconcentrations increased in mimic wastewater which were higher concentrations of Nand P. The results showed the respiratory pathway had changed in rice roots, When N_T<4. 28 mmol/L, P_T<0.2 mmol/L, HMPpathway weakened and EMP-TCACstrengthened with Nand Pincreasing, whereas when N_T > 4. 28 mmol/Land P_T>0.2 mmol/L, HMPpathway enhanced and EMP-TCACdeclined in pace with Nand Pincreasing. In addition, increased cyanide-resistant respiratory pathway and weakened cyanide-sensitive respiratory pathway were observed when N_T>2.14 mmol/Land P_T>0.1 mmol/L, There was a striking similarity in changing trend among respiratory intensity and EMP-TCACpathway, cyanide-sensitive respiratory pathway, cytochrome oxidase activity in treated roots, the similarity showed that Nand Pin mimic wastewater had affected respiratory intensity mainly by ways of affecting EMP-TCACand cytochrome pathway which was sensitive to cyanide.