The RNAi vector of PhGRP was constructed and transformed into petunia to identify the function of PhGRP expressed specifically in the early development of petunia anther.Compared with wild type，no obvious difference of the plant appearance was found in transgenic petunia，but most of the morphological indexes of its floral organs significantly increased.Results of the pollen grain staining and in vitro culture showed that the male fertility of transgenic lines was significantly lower than that of the wild type.Results of scanning electron microscope observation showed pollen grains of the transgenic lines were deformed，with abnormal exine decoration.Results of cytological observation showed that the tapetum developed thickly and degraded slowly in the transgenic lines，indicating that the abnormal development of tapetum might be the main cause of aborted pollen grain.