Abstract：Acne is a common chronic inflammatory disease in clinical dermatology，which often occurs in teenagers. Acne of yang deficiency type is mostly recurrent，lingering and refractory one. Inspired by the Kan-Li Theory of ZHENG Qin'an，Prof. CAO Yi believes that the pathogenesis of acne of yang deficiency type is based on yang deficiency and marked by heat syndromes，and yang constraint is the root，and phlegm blended with stasis. When the true yang in Kan is deficient，yin and cold gradually get exuberant， and Li fire is not able to restrict it，so Kan and Li fail to coordinate with each other；the center qi fails to transport and transform，and phlegm and stasis are generated internally，and then deficiency fire attacks upwards to result in the binding constraint at faces， which leads to acne. Prof. CAO Yi proposes the principle of warming and supplementing the spleen and kidney， subduing yang and astringing to the internal，warming yang and resolving constraint and treating both phlegm and stasis. Clinically，modified Jingui Shenqi Pills or Yougui Pills are often used to treat the disease，and to restore true yang and maintain ministerial fire，so it can not attack upwards to faces. Because of coordination between Kan and Li，healthy spleen qi can transport，and there is no chance for the generation of phlegm and stasis，and thus the disease can be cured.