This paper improved the digital watermark embedding algorithm based on Arnold scrambling and discrete cosine transform(DCT) transform. Firstly, encrypt the watermarking message via Arnold transform, and then make DCT transform of the original carriers image and embed the watermark message in the transform coefficients of DCT. The embed coefficient and control coefficient are determined by the Hash function according to the watermarking and carriers signal. Finally, the Yellow tea traceability system is designed and constructed on the basis of that a QR code product label technology with authorization digital watermark.