Alsophila podophyllais a second-class state-protected plant species. After surveying the populations and communities ofA. podophylla in the lowland rainforest and the montane rainforest of Wuzhi Mountains, Hainan Island, we analysed the population characteristics including age structures, spatial patterns and quantities, and the community characteristics including structures and species diversity. The findings showed that A. podophylla population age-structures in the montane rainforest demonstrated a stable type while in the lowland rainforest it was growth-oriented, but the spatial patterns of both were clumped. The average population density of A. podophylla in the lowland rainforest was as 1.7 times as that in the montane rainforest. The soil pH value had negative effects on the average population density, and total P content in soil had positive effects on it. The soil pH value was high and the total P content was low in the montane rainforest, while the case was reverse in the lowland rainforest, hence the discrepancy of pH value and total P content between the montane rainforest and the lowland rainforest accounted for their quantity discrepancy of A. podophylla populations. Besides, according to their path coefficients, the effect that pH value caused to A. podophylla population density was as 2.5 times as that total P content did, thus it meant that soil pH value was the major factor that affected A. podophylla population density. All the community structures were vertically divided into three tree layers, two shrub layers and one herb layer. The Simpson index, Shannon-Wiener index and evenness of the communities were 0.957, 5.305, and 0.811, respectively in the montane rainforest, while in the lowland rainforest they were respectively 0.937, 5.484, and 0.804. In conclusion, A. podophylla population of montane rainforest is different from that of lowland rainforest in characteristics including age-structures, spatial patterns and quantities, and in tropical forest of Wuzhi Mountains A. podophylla community structures are complex and species diversities are rich.