Based on chaotic scrambling, we proposed a digital image watermarking scheme in interpolatory orthogonal multiwavelets transforming domain. At first, the logistic chaotic mapping and arnold transformating are employed to scramble the original watermarking image, then the watermark information is embedded into the middle frequency interpolatory orthogonal multiwavelets transforming coefficients of the image. Experimental results showed that the scheme has high secrecy intensity and ability against the general image processing attack.