Abstract: A multiple watermarking algorithm is proposed to protect relational databases copyright for some lacks of the existing multi -watermarking algorithms.The novel multiple watermarking scheme,which embeds multi -media watermarks into relational database.The watermark embedding and extraction algorithms are specified.The algorithm is "blind" in that it isn' t requires original data in order to detect a watermark. The results of the corresponding watermark experiments and the attack experiments verify that the proposed method is correct feasible and robust.