The wet gas gathering pipelines will produce natural gas hydrate with the condition of high pressure and low temperature, which may cause blockage of pipelines or failure of key control equipment. Adding alcohols Thermodynamic?Inhibitor(THI) is one of the feasible proposals to prevent hydrate formation. If the amount of THI is poured excessive, the costs of procurement, transportation, storage and water treatment will increase in large quantities. Therefore, it is significant to determine the minimum dosage of THI based on a reasonable safety margin. Calculation of THI injection dosage based on empirical formula method and phase equilibrium software, without considering the effect of flow. In this paper, a method coupling of phase equilibrium and flow was used to optimize the injection dosage of THI. Based on the OLGA component tracking model, the temperature, pressure and THI concentration along the line are tracked, and then the THI dosage was predicted more accurately. Taking the gas gathering pipeline of land and submarine as an example, different calculation methods were compared. The results show that the new method can reduce the THI consumption by more than 10%.