Abstract: Carbon-oxygen isotopic characteristics of authigenic dawsonite can provide important geochemical evidence for its origin research. Based on carbon-oxygen isotope analysis of dawsonite from Wuerxun Depression, Hailaer Basin and Gudian Structure in Songliao Basin, combined with carbon-oxygen isotopic data reported in China and overseas, carbon-oxygen isotopic characteristics of authigenic dawsonite and its origin significance are discussed in this paper. It is indicated that the range of dawsoniteδ13C value are –5.3‰～–1.5‰PDB and –1.9‰～+0.3‰PDB respectively in Wuerxun Depression of Hailaer Basin and Gudian Structure of Southern Songliao Basin. These values are within the range of inorganic carbonaceous substance δ13C distribution(–9.0‰～＋2.7‰). Furthermore, the calculated δ13C values of CO2 gas in isotope equilibrium with dawsonite range from –10.7 to –7.0‰PDB and from–8.7 to –6.9‰PDB respectively in Hailaer Basin and Songliao Basin, which showes that CO2 of forming dawsonite originates from inorganic background. In geological background, CO2 of forming Dawsonite almost belongs to magmatic origin, with the carbon isotope range from –5.5 to ＋4.5‰PDB. Dawsonite in Hailaer Basin and Songliao Basin is diagnostic mineral recording migration and accumulation of CO2 with magmatic origin. The calculated formation water δ18O value during dawsonite deposition range from –14.3 to –9.4‰, representing the characteristics of meteoric water. The calculated isotopic temperature of dawsonite is between 52.7℃ and 93.6℃, generally in accordance with palaeo-stratum temperature(65.4～87.6℃).