According to the analysis of the chemical and isotopic compositions of the gas and combined with the hydrogeological data, this paper analyzes the geochemical characteristics of the escaping gas from the drill holes and adits of the fault zone at Chipwi dam site in Burma and explores the formation of the gas and its impact on the project. The result reveals that the gas consists of two types, that is, CO2 and N2. The deep origin of CO2 is an evidence of the geological activity of the Nmai Hka fault zone at the dam site. The gases are mainly emitted from the riverbed and their output large, having a great impact on the dam site project disposal.