Abstract: Based on the study of the variation of chlorophyll content and RUBISCO activity of seedlings in different photo-habitats, this paper studied the photo-plasticity and adaptability to forest shady of the dominant species seedling of secondary forest succession. The chlorophyll content increased as tile illumination became weaker, but the chlorophyll content decreased, if the seedlings grew in weak illumination habitats for long time. But these variations were different among tile dominant species seedlings in different forest successional stages. The results showed that the tolerant shade degrees were Cryptocarya concinna (late tree) > Castanopsis fissa (transitional tree) > Shima superba (also transitional tree) > Pinus massoniana (pioneer tree). The activity of RUBICO of Pinus and Shima increased as the illumination stronger. But the activity of RUBICO of Cryptocarya was the highest in l-hour sunshine a day (like forest gap habitats). Middle and late successionals grew better in 1-hour sunshine a day habitat, except Pinus seedlings. The tolerant shade seedlings could grow better in the forest gap habitats, because the sunshine could activate their activity of RUBICO, and the short sunshine didn’ t bleach the chlorophyll.