A new robust watermarking based on DCT domain was proposed. The algorithm takes full advantage of the local correlation of the host image pixels and the masking characteristics of the human visual system. It chose DCT blocks by comparing the value of the DCT low frequency coefficients and the amount of the nonzero DCT coefficients of each block. After the embedding process was completed, the transformation of the DCT coefficients from the frequency domain to the spatial domain produces some rounding errors, because the conversion of real numbers to integers would cause some information loss. This paper used genetic algorithm to deal with the rounding errors. The experimental results have shown that the algorithm can not only ensure the quality of the embedded image and the invisibility of the watermark, but also give robust to common image operation.