Abstract: Objective To observe the effect of fast-acting spray for heat stroke, a preparation of traditional Chinese drugs, in enhancing the heat tolerance in rats. Methods Thirty SD rats were randomized into 3 groups(with 10 in each group), and group A was treated with the fast-acting spray for heat stroke, group B with chlorpromazine, and group C with cool boiled water, before they were exposed to heat at 41℃ in a heat chamber with relative humidity of 70% till death. The rats’ rectal temperature was measured before and 1 h after the heat exposure, and the time when death occurred in the rats was recorded. Results In comparison with group C, the rats in groups A and B had lower rectal temperature and prolonged survival time with decrease mortality. Conclusion The fast-acting spray for heat stroke we prepared may enhance the heat tolerance of rats.