Abstract: It is impossible to access the information of natural gas water content directly only by the online natural gas water dew point measurement. A program is developed to calculate the water content and water dew point of natural gas based on SRK equation of state, and is successfully applied to predict the natural gas water content during the initial production period in Central Asian Natural Gas Pipeline. The simulated results are in good agreement with those presented in the literatures, with the maximum absolute deviation to predict water content of 3 mg/m³ and the maximum absolute deviation to predict water dew point of 0.5 C. A reasonable range of flowrate ratio for the two gas sources is defined as 0.26 to 0.57 by using the program to guarantee the quality of mixed natural gas at the inlet of the Central Asian Natural Gas pipeline under the conditions of one of the unqualified gas sources during the initial running period of this pipeline. It is proved safe and no liquid condensed to transport the natural gas with the flowrate ratio of the two gas sources in this range by the field data.