Abstract: Aiming at the problem that compressed domain audio steganography algorithm is very complex and has smaller embedding capacity,a kind of post-type algorithm based on MP3 was proposed.This algorithm selectes embedding position adaptively,uniformly and randomly according to the number of secret bits and the number of small-value area groups that use Hb code tables.The algorithm realizes embedding secret information through changing the last bit of carrier-codes.There is no need to decode but only to find the embedding positions and extract the last bit of carrier-codes for extracting secret information.In terms of capacity,the algorithm lifts exceeding three times than classical MP3stego algorithm.In terms of imperceptibility,the algorithm lifts 10% than code-mapping algorithm.In addition,the algorithm greatly improves the efficiency because there is no need to decode.The experimental results prove that the algorithm has the features of safety and timeliness,and can satisfy the need of secure communication.