To explore the physiological mechanisms of stresses on nitrogen metabolism and protein accumulation in wheat grains, a pot experiment was performed at the Scientific & Educational Park of Henan Agricultural University from 2010 to 2012. Zhengmai 366 and Yunong 949, wheat cultivars with different gluten-strengths, were grown in 24-cm pots with 10 kg loam soil for the experiment, which was performed using a completely randomized design in three replicates. Plants were initially grown in the field environment and were then transferred to a climate-controlled greenhouse for the high temperature (HT) treatment. HT began from the 8^th day after anthesis (DAA) and ended at the 11^th DAA, with a high temperature of 38℃for five hours from 11:00 to 16:00, after which the plants were returned to the field environment. The concentration of protein and its components, and the activities of glutamine synthetase (GS) and glutamic-pyruvic transaminase (GPT) in the grains were measured to evaluate the effects of the stresses. The results showed that HT, drought stress (DS) and their combination significantly increased protein and its components' concentrations, yet decreased the ratio of glutenin to gliadin. The protein accumulation was also reduced by stresses. For example, for Zhengmai 366, the protein yield significantly decreased by 20.7% under HT, by 16.2% under DS, and by 26.1% under a combination of HT and DS. In Yunong 949, the protein yield decreased by 12.4% under HT, by 11.9% under DS and by 15.8% under a combination of HT and DS. The grain weight significantly declined by 23.2% under HT, by 18.0% under DS and by 29.9% under a combination of HT and DS, in Zhengmai 366, and decreased by 24.0% under HT, by 16.0% under DS, and by 29.9% under a combination of HT and DS, in Yunong 949. However, the activities of GS and GPT were promoted under HT, DS and their combination. A correlation analysis showed that the activity of GS was positively correlated with the protein concentration in mature wheat grains at significant or extremely significant levels at 8, 17, 23, and 29 DAA. However, GS activity was negatively correlated with protein yield at extremely significant levels at 23 and 35 DAA, and it was negatively correlated with grain yield at significant or extremely significant levels at 8, 17, 23, 29 and 35 DAA. The activity of GPT was positively correlated with protein concentration at extremely significant levels at 11 and 17 DAA. However, GPT activity was negatively correlated with protein yield at extremely significant levels at 8, 17 and 23 DAA and negatively correlated with grain yield at significant or extremely significant levels at 8, 11, 17 and 23 DAA. The results also indicated that, under the present experimental conditions, the influence of the HT treatment was greater than that of the DS, and an overlap effect existed between HT and DS. In addition, Zhengmai 366, a high-gluten cultivar, showed more sensitivity to stresses than Yunong 949, a mid-gluten cultivar. These results may aid in understanding how HT and DS influence protein accumulation and may be useful in improving wheat quality.