1. A vector decoding method operating on a vector decoding apparatus, the method comprising: decomposing a code of an initial vector to obtain a sign code and an absolute vector code; decoding the sign code to obtain a sign vector; performing multi-level permutation-based decoding on the absolute vector code to obtain an initial absolute vector; and combining the sign vector and the initial absolute vector to obtain an initial vector, wherein each respective vector has a plurality of elements; wherein the performing multi-level permutation-based decoding step on the absolute vector code to obtain an initial absolute vector includes: decomposing the absolute vector code to obtain a position code of an element of the plurality of elements from the absolute vector in an upper absolute vector; decoding the position code to obtain position data of an element of the plurality of elements in the upper absolute vector; obtaining from a preset decoding table a number of elements in the upper absolute vector and any element value of elements removed in obtaining the absolute vector; arranging the elements of the upper absolute vector in accordance with the position data; providing the element value of the removed elements at a remaining position, to obtain the upper absolute vector; and if the upper absolute vector is not the initial absolute vector, proceeding with the multi-level permutation-based decoding on the upper absolute vector.