Abstract： Professor MAO Dexi clinically divides the insomnia into six syndrome types， namely earth failing to control fire， yin- yang disharmony， internal harassment of phlegm- heat， deficiency of kidney essence， yin deficiency with effulgent fire and blood stasis due to qi stagnation. He applies modified treatment of Fengsui pills， Erxian tang， Huanglian Wendan tang， Dushu pills， Tianwang Buxin pills and Xuefu Zhuyu tang respectively for treatment. Enumerating typical clinical cases， this paper summarizes syndrome differentiation skills， treatment methods and commonly used prescriptions of Professor MAO treating insomnia.