Objective To investigate whether poly arginine as the carrier can carry foreign proteins to penetrate the cell membrane and even penetrate the eyeball barrier.Methods Poly-Args (R9) was used as a CPP in this study.R9-green fluorescent protein (GFP) and GFP were constructed.In vitro,human lens epithelial cells were treated with these two proteins.Then,MTT assay were used to detect whether the protein could affect the proliferation of the cells.Flow cytometry and laser confocal microscopy were used to detect the penetrability of CPPs on the cells.In vivo,eyes of mice were treated with protein in eye drops way for 7 days.Then total protein were extracted,ELISA were used to detect the penetrability of CPPs.Results The results of MTT,flow cytometry and laser confocal microscopy showed that CPPs could carry protein into cells in a dose dependent manner without affecting cell proliferation.In vivo,slit lamp showed that the mice eyeballs had no any abnormal after treated by GFP,R9-GFP,and ELISA results also showed that R9 could effectively get foreign protein into the eyeball.Conelusion R9 can carry foreign protein into the cell membrane and eyeball barrier.This study provides the basis for the eye medication and dosing mode improvement.