In this paper, a kind of two-dimensional coupled ch aotic transcendental map (TCCTM) was proposed. Firs tly, by using the TCCTM chaotic sequences were generated, t hen the chaotic sequences were modified to generate chaotic key stream that is more suitable for image encrypti on. In the process of encryption, an original color image was decomposed into three images of red, green and blue components, and encrypted them in a different way respectively. The experimental results demonstrate that the extremely sensitive to the key, the encryp ted image has random-like distribution behavior of grey values, t he adjacent pixels have zero co-correlation propert ies. Furthermore, the algorithm shows the advantages of large key space and high speed of encryption