Biodiversity conservation is one of the most important service functions of wetland ecosystem in the Sanjiang Plain, moreover, it shines an important economic value in providing people with a variety of materials and services such as plant products and by products, climate regulation, soil formation, water supply and conservation, education and scientific research, recreation and so on. There are numerous factors influence the biodiversity conservation valuation results such as the rate of economic development, the changing rate of biodiversity conservation function, the discount rate, and the marginal price change of the service, etc., but few studies focused on them in the past. This article tries to discuss some problems underlying the ecosystem service valuation by employing the economic model put forward by M. Hoel and T. Sterner, to analyze the value changing process of the biodiversity conversation under the combined effect of the discount rate and the marginal price change, to study the impacts of the marginal elasticity of utility to income and the elasticity of substitution on the discount rate and the marginal price change, and to reveal the huge economic value of the biodiversity protection by comparing to the traditional Ramsey discounting method. The results showed that the value curve using Ramsey discounting method displayed gradually declining trend and the total value of the biodiversity conservation was only 1000.2 yuan(RMB) per person, while the value curve using the economic model displayed increasing at first and then gradually declining under the combined effect of the discount rate and the marginal price change, and it turned out that the total economic value of the biodiversity conservation was about 19438.9 yuan(RMB) per person. The study not only suggested that the wetland ecosystem biodiversity conversation contains the huge economic value but also proved that immediate wetland protection and recovery actions are needed so as to avoid the ever-increasing cost of the continuous wetland ecosystem damage. As the parameter values in the model may bring somewhat of uncertainty and imprecision we put forward the potential value range of the parameters to improve the accuracy and reliability of the results. The impact analysis showed the marginal elasticity of utility to income and the elasticity of substitution greatly influenced the valuation results and related decision-making on the wetland conservation. The lower the marginal elasticity of utility to income and the elasticity of substitution, the lower the combined effect of the discount rate and the marginal price change, and the higher the economic value it reveals. It can be believed that the relatively lower value of marginal elasticity of utility to income and the elasticity of substitution may realize the reasonable results. Our results also proved that it is essential to speed up the recovery of biodiversity conversation function with the rapid economic development for the coordination development of regional economy and the improvement of human society welfare.