This paper presents a blind watermarking algorithm based on quantization index modulation (QIM) and singular value decomposition (SVD) in the wavelet domain. Obtain approximation sub band of the wavelet domain coefficient matrix by performing a wavelet transform on host image. The QIM technique determines the quantization step for each embedding block. The SVD technique is modified the SVs of each embedding block. The watermark encrypted by a chaos sequence generated by Lorenz chaotic system is embedded the host image. The experiments show that this paper presented algorithm in various attacks against the image has good robustness especially for against geometric attacks and image compression.