A method for coding a speech signal, comprising: obtaining the pulse distribution of the speech signal, on a track, of the pulses to be encoded on the track, by collecting the statistic about the positions of the pulse, the pulse distribution comprises quantity of positions with a pulse, distribution of the positions with a pulse on the track, and quantity of pulses in each position with a pulse; generating a coding index that comprises a first index I1, a second index 12 and a third index 13 for identifying the pulse distribution according to the pulse distribution, wherein: the first index is adapted to identify all possible distributions of the positions with a pulse on the track when the quantity of the positions with a pulse is determined; the second index is adapted to identify a distribution, corresponding to the distribution of current position with a pulse, of all the possible distributions corresponding to the first index; the third index is adapted to identify the quantity of pulses in each position with a pulse; wherein, the generating a coding index that comprises a first index I1, a second index 12 and a third index 13 for identifying the pulse distribution according to the pulse distribution comprising: determining the first index I1 according to the quantity of positions with a pulse; determining the second index 12 according to the pulse distribution of pulse positions on the track; determining the third index 13 according to the quantity of pulses in each position with a pulse. obtaining the pulse distribution of the speech signal, on a track, of the pulses to be encoded on the track, by collecting the statistic about the positions of the pulse, the pulse distribution comprises quantity of positions with a pulse, distribution of the positions with a pulse on the track, and quantity of pulses in each position with a pulse; generating a coding index that comprises a first index I1, a second index 12 and a third index 13 for identifying the pulse distribution according to the pulse distribution, wherein: the first index is adapted to identify all possible distributions of the positions with a pulse on the track when the quantity of the positions with a pulse is determined; the second index is adapted to identify a distribution, corresponding to the distribution of current position with a pulse, of all the possible distributions corresponding to the first index; the third index is adapted to identify the quantity of pulses in each position with a pulse; wherein, the generating a coding index that comprises a first index I1, a second index 12 and a third index 13 for identifying the pulse distribution according to the pulse distribution comprising: determining the first index I1 according to the quantity of positions with a pulse; determining the second index 12 according to the pulse distribution of pulse positions on the track; determining the third index 13 according to the quantity of pulses in each position with a pulse. the first index is adapted to identify all possible distributions of the positions with a pulse on the track when the quantity of the positions with a pulse is determined; the second index is adapted to identify a distribution, corresponding to the distribution of current position with a pulse, of all the possible distributions corresponding to the first index; the third index is adapted to identify the quantity of pulses in each position with a pulse; wherein, the generating a coding index that comprises a first index I1, a second index 12 and a third index 13 for identifying the pulse distribution according to the pulse distribution comprising: determining the first index I1 according to the quantity of positions with a pulse; determining the second index 12 according to the pulse distribution of pulse positions on the track; determining the third index 13 according to the quantity of pulses in each position with a pulse. determining the first index I1 according to the quantity of positions with a pulse; determining the second index 12 according to the pulse distribution of pulse positions on the track; determining the third index 13 according to the quantity of pulses in each position with a pulse.