Secret sharing is a very important branch in the field of modern cryptography. Secret image sharing technology is the expansion of secret sharing in terms of image. When using this technology to share images, it can ensure the integrity and security of the image. In this paper, secret image used random shadow image which is generated from (t, n) threshold secret image sharing scheme. This paper adopted improved method of LSB to hide the secrets in n meaningful cover images that were provided randomly, which reflected good invisibility, then compared the level of similarity of extracted watermark and original watermark, and eventually got good effects. Finally, we made noise and cutting attack, which illustrated that the scheme has good robustness.