Abstract: For encoding binary images,binary image encryption using logic operations based on interferometer was presented to overcome the shortcomings of the previous binary image eneryption.Firstly,a binary image which carries certain information is chosen as encrypted image.Secondly,a key which is used for decrypting image is obtained using logical relationship between them.Finally,the decrypted image is reconstructed with the principle of optical interference.Computer simulation and optical experiment show that eneryption is very convenient and decryption system is simple.Also,this method can realize multi-authentication,so safety performance is very high.