Inhibitory effects of mercury chloride (HgCl , 25 μM, 50 μM and 100 μM) on the activity of aquaporins (AQPs) were investigated by comparing two wheat (Triticum aestivum L.) cultivars with different drought resistance. Leaf photosynthetic rate (Pn), transpiration rate (Tr) and leaf water use efficiency (WUE = Pn/Tr) were measured. Our results showed that Hg toxicity repressed Pn, Tr and WUE  in both ‘Shi4185’ (S4) and ‘Jinmai 47’ (JM). However, the regulation model of Pn, Tr and WUE  was different between the two cultivars. Drought tolerance cultivar ‘JM’ showed a higher Hg toxicity tolerance than the irrigated land cultivar ‘S4’. Our results suggested that different Hg tolerance in the two cultivars is related to the different activity of AQP. Our study provides insight into the complicated mechanism of drought resistance and water-saving in wheat.