A new scheme based on discrete cosine transform and its inverse is proposed to realize the discrete multitone modulation (DCT-Based-DMT) system. We use the IDCT/DCT to construct the DMT system by replacing the IFFT/FFT transform to complete multi-carrier modulation, and then analyze the peak to average power ratio (PAPR) performance of the proposed system. Based on these results, an energy compressional DCT algorithm is proposed to reduce the PAPR of the DCT-Based-DMT system. The comparison with the selected mapping algorithm based DMT system (SLM-FFT-DMT) demonstrates that the proposed DCT based DMT system (DCT-Based-DMT) with DCT algorithm provides 1.5dB PAPR reduction and lower complexity.