To investigate the role of GH3.9 in plant growth and development,we cloned the 1 750 bp full-length gene with RT-PCR method and obtained GH3.9ox-3 and GH3.9ox-9 pure lines of Arabidopsis thaliana by constructing pEGAD-GH3.9 overexpression vector and transforming A.thaliana.After treating the sowed wild-type and mutant seeds (GH3.9ox-3 and GH3.9ox-9) with blue,red and far-red light at different intensity,we found that:the growth of hypocotyls in the mutants was more sensitive to the strong light suppression comparing with wild-type.Moreover,the hypocotyls of mutants appeared to grow slower when treated different forms of white light.The mutants plant sizes and silique sizes appeared smaller.The results indicate that GH3.9 gene might play an important role in the growth and development of plants.