The invention provides a signal processing method used for sound signal code comprising: receiving sub-band sample of singal which is converted; partitioning and quantizing the sub-band sample into multiple quantization index; allocating the code book to the multi-group quantization index based on the local feature of the quantization index, therefore the application range of the code bood is foreign to the block quantizing border. The method can be applied for processing signal, such as multichannel sound signals, video signal. The code book is allocated based on the quality of the quantization index to transfer the quantization index into code bood index, therefore the selected code bood is more suitable for the quantization index and the quantization index is transfered only by less bits.