Abstract: Abstract: This study aims to explore the effect of flooding and waterlogging at the jointing stage of summer maize on the formation mechanism of yield in the Huaibei plain. Taking Denghai 605 as the test material, two treatments of water stress (including flooding and waterlogging) were carried out in a field experiment in the Wanbei experimental station of Anhui Agricultural University in 2018 and 2020. The normal water supply was also used as the control (CK). The parameters were analyzed, such as growth process, photosynthesis traits, dry matter accumulation, lodging resistance traits, male-female interval, ratio of leaf to grain, and yield of summer maize. The results showed as follows. 1) The duration from the jointing to silk and anthesis-silking interval were significantly (P<0.05) increased, compared with the CK, and the flooding treatment was significantly (P<0.05) greater than the waterlogging treatment. 2) The leaf area per plant, the chlorophyll content, and net photosynthesis rate (Pn) from the big trumpet to dough stage significantly (P<0.05) decreased in the flooding treatment, compared with the CK. The leaf area per plant from big trumpet to dough stage significantly (P<0.05) decreased in the waterlogging treatment, compared with the CK. The chlorophyll content and net photosynthesis rate only at big trumpet stage significantly (P<0.05) decreased in the waterlogging treatment, compared with the CK. 3) The dry matter accumulation of leaf, stem, ear, and whole plant from the big trumpet to maturity were significantly (P<0.05) reduced in the flooding and waterlogging treatment, compared with the CK. The dry weight of the whole plant is the most critical physiological index affecting the yield, and the rates of decrease were 53.99% and 23.65% for the dry matter accumulation of whole plant in the flooding and waterlogging treatment, respectively.4) The stem diameter and puncture strength were significantly (P<0.05) reduced in the flooding treatment compared with the CK. Meanwhile, the lodging rate significantly (P<0.05) increased in the flooding treatment, where the rate of increase was 78.53% compared with the CK. 5) The empty rods rate significantly (P<0.05) increased in the flooding and waterlogging treatment compared with the CK. The number of grains per ear is the most critical yield component factor affecting yield, and the grains number per ear and yield of summer maize significantly (P<0.05) decreased in the flooding and waterlogging treatment, compared with the CK, where the rates of decrease for the grain number per ear were 44.48% and 30.61%, respectively, whereas, those for the yield were 57.26% and 34.68%, respectively. The 1000-grain weight and the leaf area and number of grains per leaf were significantly (P<0.05) reduced in the flooding treatment, while, that significantly (P<0.05) increased in the waterlogging treatment, compared with the CK. The findings can provide a theoretical and technical support to the decision-making on the summer maize production in areas prone to the waterlogging disaster.