Abstract: We studied the usefulness of wetland plants in three Dai villages, Manjing, Man’an and Mansan, all in Xishuangbanna, Yunnan Province. Each village had varied environmental conditions and cultural traditions. We examined differences in the knowledge of using and conserving wetland plants between different age groups and between different genders. Our results showed that: (1) Dai people of Xishuangbanna used a wide range of wetland plants, including 46 families and 102 species, of which hygrophytes (helophytes) are the dominant group. The use of wetland plants can be divided into three categories: food source, medicinal use, and religious purposes, of which food source was the most common use. (2) The number of species used traditionally was higher in Mansan than in Man’an or Manjiang. Few plants were commonly used in all three villages. This variation in wetland plant use correlated closely with vegetation types near each village and the land use history of each village. (3) Knowledge for the use of wetland plants in the elder group (>45 years of age, P<0.05) of the three villages was remarkably more vast than in the younger groups (≤45), and the knowledge difference between genders had a close relationship with environmental conditions and economic status in the villages. We further discussed the relationship between plant diversity and traditional cultural diversity. Our results suggest that transmission and inheritance of ethnical culture plays a very important role for the conservation of plant diversity.