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With harvest method and caloric value analysis, this paper studied the caloric values, standing energy, net fixed energy and net standing energy increment of three plant communities i.e., grass, Dicranopteris dichotoma and Rhodomyrtus tomentosa, in Hong Kong. The results showed that the caloric value was higher in D. dichotoma community and lower in grass community. The standing energy of plants in grass, D. dichotoma and R. tomentosa community was 18,638, 38,436 and 65,632 kJ.m-2; net fixed energy was 13,286, 20,354 and 18,784 kJ.m-2.yr-1; and net standing energy increment was 3437, 9626 and 6695 kJ.m-2.yr-1, respectively. Compared with southern subtropical evergreen broad-leaved forest, the standing energy, net fixed energy and net standing energy increment were lower in grass, D. dichotoma and R. tomentosa communities, which resulted from deforestation and other human disturbance. This indicated that vegetation conversion due to human disturbance would reduce the utilization coefficient of solar energy. Net fixed energy was also found to be reduced significantly with increasing intensity of human disturbance.