A Nogo-A to Nogo-66 receptor (NgR) has been well known to contribute to the inhibition of the neuriteregeneration of adult central nervous system neurons aftertraumatic injuries.Thus, Nogo-66/NgR have been considered essential targets in axonal growth therapy.We identified a specific NgR-binding peptide (XIYXXLV, named P2) from a phage display heptapeptide library with NgR after four rounds of biopanning.The peptide P2 contained two (IY) amino acids identical and found high homology to the peptides of the nogo-66 (1-7,RIYKGVI) ,at the same time also existed another two (LV) amino acids are similar to the nogo-66 (27-33,AISEELV), which could compete with nogo-66 binding to the NgR.Functional analyses indicated that P2 specifically competed with the corresponding phage clone P2 for binding to NgR.In addition, we discovered that the P2 would reduce the inhibitory effects of Nogo-66 on neurite outgrowth in differentiated PC12 cells in vitro, and these data also suggested that the P2 could bind to NgR and activate the rho-associated coiled coil-containing protein kinase (ROCK) to inhibit neurite outgrowth by western bolt.Therefore, the results indicate that peptide P2, acting as a Nogo-66 receptorantagonist, is a promising therapeutic agent forthe treatment of spinal cord injury and even neurodegenerative diseases.