The work aims to propose an adaptive blind watermarking algorithm resistant to printing and scanning based on QR code. Firstly, the carrier QR code was processed by three-level DWT transform and the low-frequency part was subject to 4×4 block Schur decomposition. Then, the binary watermarking information was adaptively embedded into the carrier QR code based on a stable coefficient difference of sub-block U matrix. Finally, the watermarking information was extracted from the QR code which was printed and scanned. Meanwhile, the algorithm was blindly extracted. The experimental results showed that the algorithm could better resist print-scan attack, and it had higher robustness in resisting the attacks like Gaussian noise, salt and pepper noise, speckle noise, Poisson noise and JPEG compression. With strong performance in resisting prin-scan attack, the algorithm can be widely applied in the copyright protection of digital products.