Gas hydrate formation in well hole will block up oil pipes so as to affect normal production. By reference of documents, we conclude the formation conditions of gas hydrate in gas well hole, controlling factors as well as prediction methods. Based on temperature and pressure in gas wells and simplified Newton thermodynamics prediction methods of gas hydrate formation, we set up a prediction model of gas hydrate formation, and compiled the software to calculate gas hydrate formation in two cases. The calculated results suggested that the model would be a preferable prediction of gas hydrate formation.