Abstract: Seedlings of tomato cultivar ‘Moneymaker’ were used as test materials.Fusarium oxysporum f.sp.radicis-lycopersici（Forl）was inoculated with artificial inoculation method,root protective enzyme activity and defense-related gene expression,morphology,physiology and related genes expression of seedlings were studied after inoculation,the effects of Forl inoculation on seedling growth were studied,in order to provide reference for prevent the disease.The results showed that after 12days of inoculation,the main growth indexes of tomato seedlings were significantly lower,and the disease index was up to 62.3%.With the increase of inoculation days,the root activity of seedlings in both inoculation and control treatments increased,but the increase of inoculation treatment was slow,and were significantly lower than control in 6days and 12days.SOD and CAT activities were significantly higher than those of the control.Furthermore,the relative expression levels of ethylene signal marker genes ETR4 and Pti4 increased significantly with the increase of inoculation days.The relative expression key gene ICSfor salicylic acid synthesis,increased significantly,while the relative expression of PALchanged slightly.The response of PR1a defense signal gene was strong,and its relative expression was up to 200 times.The relative expression of protease inhibitor gene PI-1 had no change.