Abstract: The study was related on the analysis of community composition and diversity of nematodes in the rhizosphere soil of Japan cedar (Cryptomeria fortunei) in Western Tianmu Mountain in Zhejiang province, China. The result showed that the density of the nematodes in the genus of Rhabditis was higher than that in other genera, no matter which height above sea level (ASL) at 500m and 1000m. However, the nematodes in the genera of Cephalobus, Eucephalobus, Prismatolaimus, Acrobeloides, Acrobeles, Chiloplacus, Dorylaimus, Tylenchus and Trichodorus were found only at 500m altitude where the average of annual temperature was 16.3℃. Only the nematodes in the genus of Alaimus could be found at 1000m ASL, where the annual temperature in average ranged from 8 to 12℃. At 1000m ASL, the nematodes in the genera of Rhabditis, Aphelenchoides and Mesodorylaimus belonged to the extremely abundance group and Aphelenchus, Meloidogyne and Paratylenchus nematodes belonged to rarely group. The indexes of Shannon-Wiener diversity index (H′), Species Richness (SR) and Simpson evenness (E) at 500m ASL were higher than that of at 1000m ASL. At altitude of 500m, the proportion of bacterivore nematodes was the highest, whereas at 1000m, the proportion of predators-omnivores was the highest. Both WI (Wasilewska Index) values were greater than one, which shown the soil was healthy in Western Tianmu Mountain at the two altitudes.