H.264 has been widely used in recently years. The entropy coding method used in H.264 is contextbased adaptive binary arithmetic code (CABAC). Although CABAC can achieve high compression, it is very sensitive to channel errors. In this paper, a novel joint arithmetic and variable length decoding algorithm based on CABAC was proposed. The transmitted sequence bits were first decoded by a joint source channel arithmetic decoder, the output of which was decoded by joint variable length decoder (JVLD). The trellis graph was used to search the best symbol sequence. Furthermore, at the process of joint arithmetic decoding, the searching path was canceled if the decoded sequence did not conform to the vlc structure, thus achieving better decoding performance.  Experimental result indicates that the proposed algorithm is superior to the separate scheme.