With the aid of the Free-Air ozone Concentration Enrichment (O₃-FACE) system, effects of elevated atmospheric ozone (pO₃) on topsoil (0~20 cm) aggregate, bulk density, porosity and contents of nitrogen, phosphorus and potassium of paddy soil were investigated. The paddy field had been under rice/wheat rotation and exposed to elevated atmospheric ozone, 50% higher than the ambient pO₃, for three years. Results show that elevated pO₃ significantly increased 0.25~0.053 mm aggregates by 23.5% and significantly decreased < 0.053 mm slit +clay fraction by 24.6% in topsoil; obviously increased soil bulk density in the 0~10 cm soil layer and decreased the density in the 10~20 cm soil layer; decreased gas porosity by 39.8% and 32.4% in the 0~10 cm and 10~20 cm soil layers respectively, and increased capillary porosity by 9.1% in the 10~20 cm soil layer, thus altering the soil in proportion of solid, liquid and gas; reduced soil total nitrogen content by 10.5% and available potassium by 13.3%, increased available phosphorus by 40.8%, and however, did not affect much available nitrogen. It is quite obvious that long-term exposure to elevated atmospheric pO₃ will alter physical structure of the soil and biogeochemical cycle of nutrient substances therein.