To realize the optical image encryption system,which is based on joint transform correlator (JTC),and achieve high robustness against attacks, an optical image encryption scheme based on JTC and vector decomposition is proposed in this paper.In the encryption process,vector operation, which is based on the optical interference principle,on the plaintext is carried out by computer preprocessing.Then,the image is encrypted by using the JTC-based optical image encryption system,and the joint power spectrum is recorded as the encrypted image.For decryption,the ciphe r text is decrypted with one of the keys first.Then,the decrypted pure phase image and the other key which is directly related to the plaintext,are coherent with each other,achieving the original image.Compared with the classical JTC-based optical image encryption system,an extra key,which is related to plaintext,is used to enhance the security of the encryption system.The optical image encryption system is easy to realize.The plaintext related key is added to improve the security by vector decomposition which can remove the linearity between the cipher text and the plaintext.Furthermore,several numerical simulation results and analysis are carried out to demonstrate the validity and security of the proposed scheme.