Taking tomato（Solanum lycopersicum L. ）cultivar‘Liaoyuan Duoli’as text material，this paper selected white light（W），and the other 3 LED light sources：red（R），blue（B）and green（G）to form 6 different combined light R9B1（9∶1，the proportion of the number of lights，the same below），R8B2，R7B3，R9G1，R8B1G1，and R7B2G1；and studied the effects of different LED light sources delayed supplementary lighting on tomato seedling growth in winter and spring solar greenhouse．The result showed that supplementary lighting of LED light source could promote the growth of tomato seedlings by different degrees．Among them，the effect of R7B2G1 was the most significant．Compared with the contrast without supplementary lighting，tomato stem diameter increased by 27.42%，fresh and dry weight of the whole plant increased by 17.84% and 30.91%，respectively and strong seedling index increased by 57.61%．In addition，seedling root system activity，chlorophyll content，net photosynthetic rate，and soluble sugar content of tomato leaves，etc. were all increased significantly．In summary，adding certain proportion of green light on red and blue lights basis could significantly promote the growth of tomato seedlings．