Caloric value, referring to the combustion heat of specific dry mass, was applied to describe energy patterns in ecological processes. Caloric value is a useful tool to study energy transfer and flow efficiency, which can provide information about plant growth, development, and competitive ability. Sinocalycanthus chinensis, the only representative of Sinocalycanthus genus belonging to the family of Calycanthaceae, is an endangered shrub endemic to China. In order to evaluate the potential of S. chinensis and co-occurring species to utilize solar energy, the ash content and caloric value in the leaves of S. chinensis and 35 accompanying species at different habitats (full sunlight, forest understory, forest edge) were analyzed and compared in Spring, Summer, and Fall. The ash content in the leaves of S. chinensis varied among different habitats, and was highest in full sun habitats, intermediate in edge habitats, and lowest in the forest understory. Ash content varied over time, and was significantly higher in October than in April and July. From April to October, the ash-free caloric value in the leaves of S. chinensis at the forest edge decreased gradually, while that under forests and full sunlight decreased first in July, then increased again in October. The dynamics of the ash content and ash-free caloric value in the leaves of S. chinensis indicated that they would be affected by the ecological factors in different seasons and different habitats. The ash content varied among plant species at different strata in the community. The herb strata had the highest ash content, followed by the shrub strata, followed by the vine strata. The tree strata had the lowest ash content. The ash content of S. chinensis was slightly lower than the mean ash content of other shrub taxa. The mean ash-free caloric value in leaves also varied across strata. The tree layer had the highest caloric value, followed by the shrub layer, followed by the herb layer, with the vine layer having the lowest caloric value. The mean ash-free caloric value in the leaves of S. chinensis was lower than that in the leaves of plant species at shrub layer. The ash content and ash-free caloric value of most plant species in the community reached a peak in October. The lower ash content and ash-free caloric value compared with the other shrub taxa might indicate that S. chinensis had low ability to transfer solar energy and turn it into organics, which might contribute to the low competition ability of S. chinensis in the community. The result could provide important information for exploring the endangered mechanisms and the evaluation of the growth and development of plant species in the community dominated by S. chinensis and before establishing the conservation strategies of this species.