The invention discloses a hierarchical coding and decoding method and the device thereof. In the embodiment of the invention, the hierarchical and coding decoding proposal adopts the steps as following, after an input signal is converted into a MLT (Modulated Lapped Transform) coefficient, according to an auditory perception model, the input signal is divided into a kernel layer signal and an enhancement layer signal, and then an overlapped and packed coding data is obtained; during decoding, according to the auditory perception model, after the weighted calculation is performed to the importance of each sub-band in the enhancement layer, the reverse MLT is performed to the obtained MLT coefficient of the kernel layer and the enhancement layer, and the decoding flow is output. Compared with the prior hierarchical coding decoding art, in the invention, the MLT is performed to the input signal, the weighted calculation is performed to the importance of each sub-band in the enhancement layer according to the auditory perception model, thus, the quality of coding and decoding is enhanced, and the problem that the input signal with high sampling rate can not be effectively processed in the prior art is solved.