Optical information processing technology has the characteristics of high speed and parallelism. The wavelength of light is short and the information capacity is large. At the same time, it has many attributes such as amplitude, phase, wavelength and polarization, which could be the carrier of multi-dimensional information. Therefore, optical encryption is of great significance in the field of information security transmission and is widely used in the field of image encryption. For multiple image encryption, this paper proposes a multi image encryption algorithm based on cascaded phase iteration and computational ghost imaging. This method can encrypt multiple images efficiently at the same time, which is simple, safe and reliable, and has less transmission data. The encryption effect of this method is evaluated by using correlation coefficient, and the effectiveness and security of this method are verified by simulation.