The experiments showed that as application of Paecilomyces gunnii(4 g/kg,2 g/kg H), the survival time of mice under hypoxia at normal pressure was prolonged. After medication of it however increased oxygen consumption induced by isoproterenol in mice could be reversed. Paecilomyces gunnii(0.1 g/kg, 0.05 g/kg iv)caused a low blood pressure and reduced heart rate of rats. Otherwise, it antagonized constriction of thoracal aorta rings of rabbit resulting from ergometrine and norepinephrine in vitro. These results suggested that Paecilomyces gunnii could decrease oxygen consumption.