Abstract: An innovative watermark algorithm against security problems of the existing watermark scheme is proposed, in which the multivariate quadratic polynomials and traditional dynamic graph are combined.First, a central map from fundamental field to extension field is designed.And then the central map is hidden by using two affine transformations and the copyright information in fundamental field are mapped to software watermark in extension field.The watermark is embedded after it is transformed into an integer.An example shows the validity of the system.