At present,chaotic communications have been widely studied.However,these researches mainly focus on the binary systems while the researches of M-ary chaotic communications are not extensive.To change the situation,a chaos M-ary modulation method based on phase plane partition of Hamilton map is proposed.Firstly,the chaotic model of Hamilton map and its phase plane features are described,and then the way of creating the chaos M-ary modulation is discussed.Next,to evaluate the proposed method,the system simulation results and analysis are given.Finally,the chaos M-ary modulation method is applied to communications. At present, chaotic communications have been been studied. Focus on the binary systems while the researches of M-ary chaotic communications are not yet exhaustive. A chaos M-ary modulation method based on phase plane partition of Hamilton map is proposed. Firstly, the chaotic model of Hamilton map and its phase plane features are described, and then the way of creating the chaos M-ary modulation is discussed .Next, to evaluate the proposed method, the system simulation results and analysis are given. Finally, the chaos M-ary modulation method is applied to communications.