In secure communication, finding bits that used for steganography is essential for effective and high-quality speech information hiding. This paper presents an adaptive speech information hiding method based on K-means, which can quickly find hidden bits. This method uses K-means algorithm to detect effective hidden bits through clustering and embeds secret information with different matrices to achieve good efficiency utilization of hidden bits. This proposed method embeds secret information according to the clustering result and the matrix coding at the transmitting end and extracts the secret information according to the corresponding embedding matrix ate the receiving end. Thereby implementing secure communication over VoIP. The experimental results indicate that the proposed method has better speech quality (PESQ is reduced by about 1.5%) while achieving a higher embedding capacity (up to 976 bit/s), and it shows strong concealment.