Abstract: According to the research about which ground level ozone hurts crops and ozone pollution tends to be serious. The ozone pollution in the greenhouses was measured the results show that due to photochemical reaction, ozone pollution is likely bo be found in greenhouses and ozone concentration may reach a hazardous level to crops. The nature of ozone in greenhouses needs further investigation. The application of gaseous ozone as biocide is a questionable practice.