Copyright protection has always been one of the difficult issues in the field of book publishing. Digital watermarking has been widely used as an important method of copyright protection. According to the characteristics of the QR code and PCA algorithm, this study proposes a digital watermarking algorithm based on QR code book copyright protection. The algorithm firstly uses Principle Components Analysis (PCA) to décor relate the QR code image pixel to obtain the principle component which contains both high frequency and low frequency, then embeds the copyright information watermark after using Arnold scrambling to these principal component factor. The experimental results show that the new algorithm has strong robustness against geometric attacks, noise, image brightness and contrast increase or decrease attacks.