The physioecology of Ranunculus bungei was investigated from 1986 to 1991 in a rapid-flowing stream in the Maoershan Mountain of North Temperate, and laboratory experiment were meanwhile designed to examine and to verify the results obtained from the field study. It is considered that light was the factor determining the photosynthesis of the plant due to the microclimate in the forest studied, and nitrogen was the limiting factor of the plant growth as the rivulet was oligotrophic. However, ice and snow had roles in eight protecting or stimulating the freezing of the plant. Microclimate area was put forward to explain the surviving of the plant over the winter and the peculiar distribution of some other aquatic plants. Regenerated niche was also raised to compare with realized niche from static to dynamic state so as to explain some particular phenomena in the growth and distribution of the plant.