A new version of the polyalphabetic encryption scheme (PES) has been proposed based on the triple vertex cycle graph (TVCG). In the current study, a new definition for TVCG is given. The PES has been modified based on the TVCG. The security in comparison with the previous symmetric encryption schemes is increased. The ciphertext of the plaintext, in the proposed PES, is sent to the receiver entity as the TVCG. Based on cycle graph Cn, the TVCG is created depending on the encrypted letters of the plaintext bits and the rules of a secret key. In the current study, a study case of the proposed TVCG-PES is presented as a new experimental result. Then, the security issues of the TVCG-PES are determined. The TVCGPES is considered as a new insight for more secure communications.