Psoriasis is a common chronic inflammatory skin disease，which has become a a clinically challenging condition because of its chronic and recurrent characteristics.Obstruction-removing therapy holds a crucial position in traditional Chinese medicine，encompassing a rich range of approaches.Applying the obstruction-removing method to treat diseases related to collateral pathology provides a new perspective and strategy for clinicians to treat various complex and difficult-to-treat diseases.In dermatology，the method of dredging collaterals，which is based on the theory of collateral pathology，has been widely used in the treatment of various chronic and stubborn skin diseases.The article provides a brief analysis of the imagery，physiology，and pathology characteristics of collaterals.It systematically elaborates on the mechanisms of collateral pathology in the development of psoriasis from the perspectives of affected areas，pathological factors，and the progression of pathological mechanisms，including the relationship between skin and collaterals，the common pathological factors of psoriasis and collaterals diseases，and the development patterns of diseases entering collaterals in chronic conditions.Accordingly，the theoretical basis of dredging collaterals in the treatment of psoriasis is specifically discussed and introduced.It specifically explores three treatment objectives in clinical applications：expelling pathogenic factors，guiding drugs to reach places，and maintaining qi and blood.The article aims to contribute to the research on the etiology and pathogenesis of psoriasis，guide clinical treatment，and improve the structure of medication.