In clinical practice，application of medicine pares with character of being opposing and complementary in treatment of constipation Theory are as follows:（1）Ascending and descending:The intestines function properly with smooth downward Qi movement.The Middle Jiao（Spleen and Stomach）serves as the pivot for the ascending and descending transport of waste.Spleen Qi governs ascent while Stomach Qi governs descent.The Liver governs ascent and the Lung govern descent.The ascent and descent must coordinate with each other，regulating the flow of Qi.In pathological conditions，when Qi movement is abnormal-either due to weakened Spleen and Stomach transportation and absorption functions or stagnant Qi-the large intestine cannot function properly，leading to retained waste and constipation.（2）Zang and Fu Organ:The large intestine is a hollow organ，responsible for transporting waste but not storing it；it can be full but not solid.Its main function is to move waste.The Lung is solid organ that store vital essence without excreting it；they can be full but not solid.The Lung prefer moisture and dislike Dryness，governing the downward movement and regulating water passages，providing the motive force for the large intestine to expel waste.Pathologically，if Lung Dryness-Heat descends to the large intestine，or its descending function fails，the large intestine cannot transport properly，which causes constipation.（3）Exterior and interior:The large intestine is hollows and belong to the exterior，while the Lung is solid and belong to the interior.The Lung and large intestine interconnect via meridians，establishing exterior-interior relationship between organs，coordinating physiologically and affecting each other pathologically.（4）Deficiency and excess:Constipation involves both deficiency and excess patterns.Heat，Qi and cold-related constipation are excess patterns，while constipation caused by deficiency of Qi，blood and Yin or Yang belongs to deficiency.Different types of constipation often overlap or transform from one type to another，with excess leading to deficiency or deficiency leading to excess.（5）Dryness and Dampness:The large intestine governs Fluid，absorbing water during waste transport to regulate bodily Fluid metabolism.If there is excess Heat in the intestines，it excessively consumes water，leading to Dryness and hard stools；if cold deficiency affects the large intestine，it fails to absorb water，leading to loose stools and other illnesses.（6）Yin and Yang:The large intestine is active and belongs to Yang；when Yang is diseased，Yin accumulates，leading to stagnation and constipation.Professor Mao Dexi proposed that in treating constipation，one should closely follow the disease mechanism，using opposing and complementary medicine pairs，emphasizing medication balance in ascent and descent；combining Cold and Heat to promoting Yang with warming medicine to relieve constipation；using attack and tonification method at the same time to strengthen Spleen and relieve constipation；combining firmness and gentleness in medicine applying to moisten the intestines and relieve constipation；harmonizing Zang and Fu to treat at top aiming at curing disease of lower part of body，i.e.regulating the bowels.All of the above show significant clinical efficacy.