Abstract: A new chaotic image encryption algorithm based on multi logistic maps(LMs) and piecewise sine chaotic maps(PSCMs) is proposed.The initial values and system parameters of the m PSCMs are generated by four LMs via iteration.By using the m-PSCMs chaotic secret key stream are generated.The image is encrypted two rounds by the chaotic secret key stream pixel by pixel and ciphertext output-feedback technology is introduced.The experimental results demonstrate that the extremely sensitive to the key and the plaintext,the ciphered image has random-like distribution behavior of grey values,the adjacent pixels have zero co-correlation properties.Furthermore,the algorithm shows the advantages of large key space and high speed of encryption.