The changes of production and pressure during the actual production of gas wells in tight gas reservoirs are complicated, and the frequent changes of working system make the production prediction difficult. The historical production data of well clusters in Sunan gas field was analyzed, the decreasing pattern of production decline at different production stages was clarified, and based on hyperbolic decreasing model, a time-varying decreasing model was proposed for the overall analysis of well clusters to compensate for the errors caused by fluctuations of single-well data, and a nonlinear adjustment parameter α was introduced to enhance the adaptability of the model to different production stages. The results show that the time-varying decreasing model can accurately capture the initial high gas production and the subsequent rapid decreasing trend in the process of well clusters production prediction, with the correlation coefficient of the predicted daily gas production of more than 0.95 and the average error of the cumulative gas production of less than 2.5%, which is significantly better than the other three decreasing models. It provides a new method for gas well production prediction in tight gas reservoirs of Sunan gas field.