On the basis of careful research on arithmetic coding and arithmetic encryption, a kind of image joint compression encryption algorithm based on improved zero-tree coding is proposed, where a key is used to modify the original context and the original decision produced in the process of image compression, and the image joint compression-encryption is realized in this way. In this work, the rule of the context modification and the decision modification algorithm is discussed and its security is analyzed. In order to meet different application requirements, different keys are used to encrypt separately the different wavelet resolution coefficients during bit-plane coding, so the resolution selective encryption is realized. Moreover, the Zero-tree coding was improved, and adaptive arithmetic coding is introduced to the improved Zero-tree coding, and then joint compression-encryption algorithm proposed is simulated. The simulation results show that the proposed image joint compression-encryption algorithm has the same compression efficiency compared with the original image compression algorithm; and the proposed algorithm has better security than the joint compression-encryption algorithm based on the interval splitting.