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Due to the stego image double compressed before embedding in some steganographic techniques, double compression could be one of the features of steganography. After JPEG double compressed, the DCT statistic of JPEG image will be changed, which is the focus in this paper. The distributions of DCT coefficients are changed with the double compression quantization tables: q1, q2 The difference of the distributions is analyzed in this paper. The different detection methods are proposed based on different q1, q2 which are effective proved by the experiments in this paper.