Abstract: The increasing of demands for securely transfer of images through the internet and wireless systems gave the importance to cryptography systems. In this paper, image encryption technique come with chaos. Lorenz and Chua chaotic systems with fractional order that produces enlarged in key space are used to encrypt image. A high robustness and security for encryption process are guaranteed by using these chaotic systems with all properties which are owned such randomness, nonlinearity and the large key space. From the results, the low Peak Signal to Noise Ratio (PSNR) (around 8 dB) when any small change in any of the system parameters and perfect PSNR for the decrypted image. That shows the encrypted key has a large sensitivity to small change in any parameters of Lorenz or Chua chaotic systems. Consequently, a high complicated image encryption is suggested using the proposed system that is shown here.