The invention discloses a novel method for lowering the breath resistance of the bronchus, which achieves the aim of treating asthma by the function of suppressing MLCK and still belongs to the first time at home and even abroad. The preparation of an MLCK gene knockout mouse and the research of the contraction function of the MLCK gene knockout mouse confirm the key function of the MLCK in the contraction of the smooth muscle of the air duct so as to confirm that the breath resistance of the bronchus can be obviously lowered under the conditions of physiology and pathology by suppressing the MLCK, thereby making a sufficient preparation for the next artificial synthesis of an MLCK suppressor used for treating the asthma. The invention not only finds the novel method for lowering the breath resistance of the bronchus but also provides a concept for developing other treatment schemes afterwards.