Changes in the yields and quality, and the physiological response of w heat (Triticum aestivum cv. `Ji'nan17' and `Lumai21') grown under low light intensities (50% PPFD) at different filling stages were studied. Wheat was p lanted in 2.5 m×2.0 m plots. The plots were shaded with white fabric that filtered 50% PPFD during three different filling stages: 1-10, 11-20, and 21-30 days afte r anth esis. Protein accumulation rate, nitrogen accumulation and distribution, kernel weight and yield, test weight, protein composition, protein content, wet gluten content, glutenin macropolymer (GMP) content, starch and protein quality were me asured. The results showed that under 50% PPFD, wheat yield and test weight deceased sharply (p<0.05), less nitrogen was distributed to kernels (p<0 .05), bu t protein content and wet gluten content increased significantly (p<0.05), esp ecially at the early filling stage. At the late filling stage, gliadin and glute nin content, glutenin macropolymer (GMP) content and glutenin/gliadin index incr eased significantly (p<0.05). Thus, farinogram parameters, such as water a bsor ption and dough stability time, improved at low light intensities (p<0.05) . Ho wever, these parameters changed only slightly during the early and middle fillin g stages (p>0.05), which suggested that the late filling stage is an impor tant stage during which light intensity influences protein quality. Shading or lower light intensity improved wheat quality, but yields decreased sharply, especiall y during the early grain filling stage. The two varieties, `Ji'nan17' and `Lumai 2 1', showed similar responses to light levels at the different filling stages. Th erefore, future investigations should be conducted to resolve the conflict betwe en differences in yield and quality.