China is the largest producer and consumer of agricultural products in the world. Maize (Zea mays L.), including both spring and summer maize, is one of the most important food crops in China and the world. Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar, and is the most basic plant physiological process directly related to crop yield. Therefore, light is an important factor affecting plant development, especially at late developmental stages. As a C₄ plant, maize is recognized as a high light-efficiency crop and its production potential is very high. Thus it is important to study the photosynthetic characteristics of maize. Traditionally, most maize is conventionally planted on the flat. Compared with flat culture, ridge planting has the advantages of increasing the soil surface area conductive to the acceptance of light, and it can improve the soil structure ofthe plowed layer and raise soil temperature, which is propitious to plant growth. Moreover, ridge planting is beneficial for irrigation purposes. However, little information is available on the photosynthetic characteristics of ridge-cultured maize. In this paper, flat and ridge planting methods were compared with determine the superior planting method for promoting the formation of photosynthetic products and increasing summer maize yield. The experiment was conducted in the experimental plot of the Xunxian Agricultural Science Research Institute during 2006-2007. Comparisons of the photosynthetic capacity, dry matter accumulation and yield of summer maize grown by ridge culture and traditional flat culture methods were analyzed. The findings provide a theoretical insight into the physiology and ecology of photosynthesis for popularizing ridge culture of summer maize. The results indicated that photosynthetic rate (Pn), leaf transpiration rate (Tr), and stomatal conductance (Gs) of summer maize were higher in ridge-cultured plants compared with those of flat-cultured plants, and their diurnal variations were represented by single-peak curves, which all reached maxima at 12:00. The diurnal variation of intercellular CO₂ concentration (Ci) was opposite to that of Pn and represented a reversed parabolic curve. The Fv/Fm ratio and Ф PSII were increased by ridge planting relative to those of flat-cultured plants. Compared with flat planting, the leaf area at late developmental stages of ridge-cultured summer maize decreased more slowly. At the jointing stage, dry matter weight did not differ significantly between treatments. However, at the silk stage, leaf and stem dry matter with ridge culture increased by 13.5% and 23.6%, respectively, compared with those of flat-cultured plants during the development of summer maize plants, and the difference declined with maturity. The leaf area index increased by 6.4% and 3.7% at the dough stage and maturity, respectively, which could efficiently increase potential light capture. This finding demonstrated that ridge planting extended the functional period of leaves, which is particularly important for accumulation of photosynthetic products and their transfer to the grain. The thousand-grain weight with ridge planting was significantly increased by 8.7% and 6.0% in 2006 and 2007, respectively, compared with flat planting, and may be the main contributor to the yield difference. Ridge planting increased yield by 9.6% compared with flat planting. Consequently, ridge planting is beneficial to achieve maximum grain-filling capacity.