Abstract: The study was conducted to assess the expression of c-Myc in pulmonary vascular smooth muscle cells in the development of pulmonary vascular remodeling in broilers induced by low ambient temperature. 120 male broiler chicks (Arbor Acre) of commercial strain were randomly allocated to control group (raised at the temperature of (22±1.5) ℃) and low temperature group (raised at the temperature of （11±2） ℃) at 15 days old. Six broilers in each group were sampled every week from 15 to 50 days of age and lungs were paraffin-embedded, sectioned. The percentage of relative medial thickness (MT%）and the percentage of relative lumen area (RLA%),the indexes of pulmonary vascular remodeling，were examined by computer-image analyzing system．Positive indexes (PI) of c-Myc in pulmonary vascular smooth muscle cells were assessed. The result indicated that pulmonary vascular remodeling were significantly elevated in low temperature group from 36 days of age (P<0.01 or P<0.05). PI of c-Myc in pulmonary vascular smooth muscle cells were significantly higher than those in the control group from 29 days of age (P<0.01). The study demonstrated that c-Myc in pulmonary vascular smooth muscle cells were expressed significantly induced by low ambient temperature and have a pivotal role in the development of pulmonary vascular remodeling.