Under treatments of different water and nitrogen applied level, the relationship between canopy water content and canopy temperature was studied. It showed that the canopy water content went up gradually with the applied water increased. But when the applied water exceeded its threshold, the canopy water content decreased, while the canopy temperature kept the same. There was negative correlation between canopy water content and canopy temperature. The canopy water content under nitrogen treatments was higher than that under non nitrogen treatments. The canopy water content of all nitrogen treatments of "Jingdong 8" decreased with the nitrogen applying quantity and the canopy temperature increased. There were different regularities in all nitrogen treatments of "Zhongyou 9507" to those of "Jingdong 8". It was practicable for using canopy temperature to judge the canopy water content.