Abstract: M-ary direct sequence spread spectrum(DSSS) system does well in improving anti-jamming ability of communication, but it puts forward higher requirements to the spread spectrum code number. In order to solve this problem, M-ary DSSS anti-jamming scheme with chaotic mapping sequence was proposed. However, the chaotic sequence of single low-dimensional chaotic mapping has some shortcomings in terms of anti attack ability, key space and security. A new mixed chaotic sequence was presented, and the anti-jamming performance with traditional direct sequence spread spectrum system based on m sequence and Gold sequence was compared. Results of performance analysis and simulation indicate that the mixed chaotic M-ary DSSS system has strong anti-jamming(the anti-jamming ability of the 16-ary mixed chaotic direct sequence spread spectrum systems is 10 dB better than traditional DSSS systems), and can meet the requirement for spread spectrum code number.