Abstract: By using the geology,logging,production performance and testing data,the comprehensive analysis on main controlling factors of high production in He-1 gas reservoir of Dingbei block,Ordos basin was carried out.The results indicate the main factor influencing the high production is the massive water produced in gas wells,while the gas-water distribution is mainly controlled by three controlling factors,namely hydrocarbon source rocks,reservoir property,and the interlayer thickness between fault and gas-water layer.Under a certain hydrocarbon-generating intensity,the reservoir with better physical properties has a higher gas saturation in natural gas,gas layers and gas-water layers are mainly distributed in reservoirs with close vertical distance to hydrocarbon source rocks,while the water layers with gas and the water layers are mainly distributed in reservoirs with long vertical distance to hydrocarbon source rocks.When the interlayer thickness of gas-water formation is smaller or when the gas layers are close to the faults,it is easy to communicate with the upper water layer in the process of reservoir reconstruction,and therefore,the production capacity would be affected.