In this paper, the Zhangye National Wetland Park and the Zhangye Heihe Wetland National Nature Reserve in the middle reaches of the Heihe River were examined in order to compare plant composition, species diversity, plant growth status, soil nutrients, soil physical and chemical properties, and the relationship between vegetation characteristics and soil properties. The results showed that plant height and soil nutrient content (organic carbon, total nitrogen, available nitrogen, total phosphorus, available potassium) in the Wetland Park were significantly higher than those in the Nature Reserve, and the soil physical and chemical properties (bulk density, pH) were significantly lower than those in the Nature Reserve, indicating that the Wetland Park is more conducive to plant growth and development, soil nutrient sequestration, and improved soil texture. The genus, abundance, and species diversity (diversity index, richness index, evenness index) of plants in the Nature Reserve are significantly higher than those in the Wetland Park, indicating that the Nature Reserve is more favorable to maintaining plant diversity. The plant species diversity index of the Wetland Park was significantly affected by soil total phosphorus and available phosphorus. The species diversity index of the Nature Reserve was significantly affected by soil salinity, indicating that the soil factors affecting plant diversity in different conservation areas were different.