Abstract: The effect of Verapamil, a calcium antagonist, on pulmonary vascular structural remodeling induced by low ambient temperature was investigated through observing the dynamic change of pulmonary arterioles medial thickness and pulmonary blood vessel endometry area caused by proliferous smooth muscle cells in broiler chickens. One hundred and fifty 15-day old commercial broiler chickens were randomly divided into 3 groups as follows: 50 birds were exposed to normal temperature (22- 24℃), 50 birds were exposed to low temperature (9-11℃), and 50 birds were exposed to low temperature (9-11℃) and received 0.01% Verapamil in drinking water. At 28, 36 and 44 days of age,10 birds were randomly taked from each group.Pulmonary arterial pressure (PAP ) was determined as index of pulmonary hypertension. The measurement of mean medial thickness in pulmonary arterioles (mMTPA) and ratio of vessel wall area to vessel total area (WA/TA) were conducted by using the microscopic image analysis program. The results showed as follows:（1）Verapamil significantly inhibited the increase of mPAP(kPa)，Verapamil was lower than low temperature group at 28, 36 and 44 days (P＜0.05); (2) at 28, 36 and 44 days of age, the mMTPA of 50-100μm pulmonary arterioles of low temperature group was obviously higher than that of Verapamil group (P＜0.05), it bears an analogy to the differences between groups in 100-200μm of pulmonary arterioles, Verapamil could inhibit the medial smooth muscular prolieration of pulmonary arterioles; (3) the WA/TA of pulmonary arterioles of low temperature group was obviously higher than that of Verapamil group (P＜0.05), Verapamil inhibited the hypertrophy of the vessel wall. In summary, the results indicated that Verapamil could inhibit pulmonary vascular structural remodeling and pulmonary artery hypertension induced by low ambient temperature in broiler chickens.