In order to study the physiological characters and the correlation between endogenous GA,IAA and growth of tomato seedling,we used light-emitting diode (LED) as light source and with fluorescent light as control.Four different monochromatic light(red light,blue light,yellow light and green light) were set as experimental treatments.The results showed that:(1)Seedlings under red light and blue light had longer stem and larger leaf area.(2)Except from the soluble sugar content and the activity of SOD of seedling under blue light,the root activity,pigment content,soluble sugar and soluble protein content of seedling under other monochromatic light treatments were all lower than the control treatment.(3)Compared with the control treatment,the GA level of seedling leaf in other treatments reduced dramatically.The IAA level of leaf under red light increased dramatically and reduced significantly under yellow light and green light.Positive correlation existed between IAA level of leaf and leaf area.(4)The GA and IAA level were both significantly higher under red light and blue light than that of the control,yellow light and green light.Positive correlation existed between IAA level of stem and stem length,also between GA level of stem and stem length.