Abstract: The long-term experiments of different O₃ concentrations on main food crops in China are conducted by using OTC-1 top-opened chambers. The results show that increasing O₃ concentration would promote rice development. The winter wheat development would be slow in early days,but fast in late time. The milk duration and plant height of rice and wheat would be shortened. The dry biomass would be decreased with the prolong of ventilation time. The water content in leaf of winter wheat would be decreased as parabola type,but there is small impact on rice. Under the same higher O₃ concentration environment,the beginning date of rice leaf injured by ozone was later than winter wheat,and the injury development slowl. With the O₃ concentration increasing,the yield of per plant and thousand grains weight would be decreased,and the loss scale of winter wheat yield by ozone is greater than that of rice. The reaction of winter wheat to O₃ concentration is more sensitive than that of rice.