Abstract： This article is to summarize and introduce Professor LAO Changhui's understanding of theoretical connotation "disease with latent pathogen induced by a new pathogen" and his clinical experience in treating cough variant asthma from the view of "disease with latent pathogen induced by a new pathogen" by syndrome differentiation. Professor LAO Changhui believes that recurrent and lingering cough variant asthma is indeed caused by lung cold and spleen deficiency，insecurity of exterior defense，repeat invasion of wind，long-going phlegm-blood stasis hidden in the collaterals，induction of latent pathogens by newly-contracted pathogens which cannot be dispelled out by healthy qi，long-term detention generated into disease and combination of the internal and external. Therefore，cough variant asthma has the attack stage and remission stage，and is treated by stages. It is advocated to scatter wind，release lung and relieve cough at the time of invasion of both new and old pathogens and struggle between the healthy qi and pathogenic qi and to warm，moisten and release gold and strengthen the vital essence when cough is relieved and the healthy qi is deficient，which can achieve a great curative effect.