Abstract: The gas-oil ratio of Lamadian, Sartu and Xingshugang region in Daqing placanticline rose up continuously, and the higher saturation pressure, gas-oil ratio and the content of CH₄ in the north are higher than that of in the south, the only gas cap isn’t in the highest structure in placanticline and the carbon isotope values of CO₂ indicate the CO₂ is from pyrolysis of carbonate in the basement. These phenomenon indicate that the gas in placanticline is in a state of moving. The deep gas source enter into Lamadian structure firstly and goes to Sartu and Xingshugang structure gradually. The results shows that there is a giant gas field in the deep of Daqing Changyuan which continuously added natural gas fie.

Key words: Daqing placanticline, dissolved gas, gas-oil ratio, carbon isotope, dynamic mechanisms