The goal of steganalysis is to detect and/or estimatepotentially hidden information from observed data.Steganalysis not only plays a significant role ininformation countermeasures, but also can preventthe illicit use of steganography. This paper developsan active steganalysis system for detecting hiddenmessages, by estimating frames with hidden messageand message length in compressed audio filesproduced by MP3Stego. Principle ComponentAnalysis (PCA) is applied not only to estimateuncorrelated components but also help to detectwhether the received MP3 streams are steganographyor original. In this steganalysis system, hiddenmessages can be detected in the PCA (whitening)stage. Independent Component Analysis (ICA)attempts to separate a set of steganographic signalsfrom original signals. By analyzing the nature ofMP3 signals (frame header, side information), framewith secret message can be detected. The results ofempirical tests reach 97% and conclude thatdetection accuracy of the proposed steganalysissystem is convenient for MP3Stego embeddedcontents. Experiments shows that the proposedmethod can be used quite effectively to detectlocations of messages embedded using nature of MP3signal