Lodging is the common problem in rice production, which causes great losses in both yield and grain quality. Rising tropospheric ozone concentration is currently one of the most important air pollutant which suppress plant growth and thus result in yield loss of crops. However little is known about effects of elevated ozone concentration ( ) on the lodging of rice and related mechanisms. Free Air gas Concentration Enrichment (FACE) system was designed to conduct gas fumigation experiments in natural fields, and spatial advantages of this technology offer the best chance for studying ozone impacts on rice lodging. In this report, a FACE experiment was conducted in a paddy field (119°42'0″E,32°35'5″N) by using an unique FACE system in the world. A two-line hybrid rice cultivar Liangyoupeijiu was grown at ambient (A-O₃) or elevated (E-O₃). The effects of elevated on lodging-related traits of rice at heading or 35 days after heading (DAH) were investigated, including lodging index, bending moment, breaking-resistant strength, culm diameter, the fresh and dry weight per unit internode length, the concentration of soluble carbohydrates and starch of different internodes (without leaf sheath). Compared to the control, exposure to elevated increased lodging index of the fifth, forth and third internodes from the top at heading by 25%, 16% and 14% respectively, at 35 days after heading (DAH) by 13%, 12% and 2% respectively. The bending moment as well as breaking-resistant strength of the fifth, forth and third internodes from the top were decreased by elevated at heading and 35 DAH, but the decreases in breaking-resistant strength due to ozone stress were larger than in bending moment. Elevated had negligible effects on internode length or culm diameter of the fifth, forth, third, second and first internodes from the top at heading and 35 DAH. However, the fresh weight and dry weight per unit length of the same internodes at heading and 35 DAH were reduced significantly by elevated , the reduction in dry weight per unit length of each internode was more significant compared with that of fresh dry weight. Elevated decreased concentrations of soluble sugar and starch of all investigated internodes at heading and 35 DAH, and the decrease was more pronounced at late grain-filling stage. The above results indicate that lodging risk of Liangyoupeijiu will increase under future high ozone conditions. The decrease in lodging resistance of rice under ozone stress was associated with weakened basal internodes, which was revealed by significant decrease of breaking-resistance strength of these internodes under elevated . The latter was probably due to poor filling of basal internodes as showed by lower dry weight per unit internode length and reduced concentration of carbonhydrates.