A novel fast method for pixel random mapping is proposed.Combining with the technology of information hiding of Least Significant Bit(LSB)，the RGB colour image used as a carrier image to hide real colour image，gray image，binary image and holography information are discussed.The experimental results show that this method has a high efficiency of encryption and decryption,and is robust to resist the attack of interference and image cutting.While the technology of LSB is applied properly according to the property of information hiding，the multiple information can be hidden well in carrier image while the quality of image is almost not influenced.