Digital watermarking technology is a kind of method to protect digital products.This paper proposes a new watermarking algorithm based on integer modulo.The features of presented method to embed the watermark are:①the difference between the watermarked and the original image is perceptually invisible;②using a secret key in the procession of embedding and retrieving the watermark;③the position for embedding is random and calculation procession for the position is irreversible;④retrieval of the embedded watermark does not need the original image;⑤the watermark is robust against LSB,BIT-COMPLEMENT^[4] and cut attack.