A kind of multi-functional digital watermarking technology based on RS error correction code and singular value decomposition is presented,which consists of copyright protection watermark algorithm and user tracking watermark algoritnm.Based on the characteristic of RS error correction code,the watermarking algorithm for copyright protection designs two different extracting methods for client and certificate authority to meet two different requirements of robustness.The algorithm of embedding watermark doesn't distinguish the two scenes,and produces an asymmetry in process of embedding and extracting,so this method can enhance protection performance and can reduce the computation complexity.The watermarking algorithm for user tracking uses a SVD quantization and grouped inserting watermark to improve robustness.Experimental results indicate that the PSNR of the watermarked image is 47.96 dB.The watermarking algorithm for copyright protection reaches the standard of strong robustness,and the watermarking algorithm for user tracking can achieve 100% extracting in certain attracting.