Abstract: 【Objective】 By analyzing the ecological niche differences and molecular characteristics of different Dendro-bium species, the genetic and ecological relationships among different Dendrobium species were revealed,which providedscientific basis for the protection and utilization of Dendrobium wild resources. 【Method】Three representative Dendrobium（D. huoshanense,D. officinale and D. moniliforme） were selected as research subjects. Species occurrence data forthese Dendrobium species in 3 major distribution areas in China were obtained through a combination of database informa-tion and field surveys. Data on 19 ecological factors were retrieved from the WorldClim database. The correlations amongthese ecological factors were analyzed,and the characteristic niches of the 3 Dendrobium species were calculated. Theinternal transcribed spacer（ITS） sequences of the 3 Dendrobium species were amplified and sequenced using PCR. Basedon the similarity of the ITS sequences of the 3 Dendrobium species,a phylogenetic tree was constructed using theNeighbor-joining method to analyze their phylogenetic relationships. 【Result】 The correlation analysis of ecologicalfactors revealed that the 7 major ecological factors were annual mean temperature,monthly mean diurnal temperaturerange,isothermality,annual temperature range,precipitation of the driest season,and precipitation of the warmest season.The niche overlap between D. huoshanense and the other 2 species,D. officinale and D. moniliforme,was relatively low,at 0.95% and 1.87% respectively,indicating that D. huoshanense had a specific ecological niche requirement. In contrast,the niche overlap between D. officinale and D. moniliforme was high,reaching 51.40%. When the 3 Dendrobium specieswere compared in pairwise, the null hypothesis of niche equivalence was not rejected（ P＞0.05）. The 3 Dendrobium spe-cies had different ecological niches at present, the possibility that they occupied similar environmental niches could not beruled out, which indicated that the mixed cultivation of the 3 Dendrobium species in the field was feasible. The overlap ofD. officinale and D. moniliforme was the most, which indicated that the environmental conditions or resource sharing de-gree of the two was the highest, and the competition was the most intense. The length of ITS sequence of the 3 Dendro-bium species ranged from 690 to 710 bp. Phylogenetic tree results showed that species alone formed 1 highly supportedgroup, while the individuals of D. moniliforme and D. huoshanense were grouped into 2 other groups with low support. 【Conclusion】 Compared with D. officinale and D. moniliforme,D. huoshanense has more specific requirements for eco-logical factors. D. huoshanense and D. moniliforme are more closely related. ITS sequence analysis can distinguish D. officinale from D. moniliforme and D. huoshanense.