Canopy temperature (CT) has been considered as a physiological indicator of plant fitness, and can be used as an effective tool in screening wheat (Triticum aestivum L.) for water use efficiency (WUE) and high yield. Field studies were conducted at Zhenyuan, Gansu, China, in 2005-2006 to examine the differences in CT and the relationships between CT to grain yield and WUE in winter wheat genotypes. Twenty three winter wheat genotypes (supplied by North China Winter Wheat Performance Tests Program) were grown under a dryland condition. CTs were recorded during early to mid-late grain filling stage between 1.30 pm and 3.30 pm on 3 clear days with a portable infrared thermometer. Genotypes showed considerable differences in CT, the differences increased with the development of plant and the maximum differences were observed at mid-late grain filling stage. Among the genotypes studied, a highly negative regression between CT and grain yield/WUE (R² =0.445-0.812) was established, no matter in early or middle or mid-late grain filling stage and the R² values increased as grain filling proceeded. Grain yield reduced by about 280 kg hm^-2 and WUE reduced by 0.6 kg hm^-2 mm^-1 respectively when CT increased 1 ℃ at mid-late grain filling stage. These results clearly indicated genotypes maintained a consistent CT after middle grain filling, indicating some genotypes with high-yield and high-WUE consistently had low CTs, whereas the low-yield and low-WUE genotypes had high CTs. Regression results suggested that, to use CT as an parameter to estimate yield and WUE, the best time to take the measurement is at mid-late grain filling stage. The highly negative regression between CT and yield/WUE also suggested that CT can be used by breeding programs as a potential selection criterion for grain yield and WUE in wheat.