Abstract: On the basis of distribution information of tropical plants in Nepal,the associations between the proportions of tropical plants and climatic factors on elevational gradient were investigated through simultaneous autoregressive models, as well as the change of the elevational patterns of tropical plants in the context of climate change. It was observed that the proportions of tropical plants were very sensitive to the coldness, especially minimum temperature of the coldest month showing the strongest explanatory power (98.7%). The freezing-tolerance hypothesis, to certain extent, was supported. Strong associations between minimum temperature of the coldest month and the proportions could be used to understand the distribution patterns and underlying mechanisms on elevation gradient. In the context climate change, mid-elevation may the most sensitive regions invaded by tropical plants, and fundamental change may be observed there.