In this study, we have analyzed the impact of COVID-19 on natural gas supply reliability. Natural gas supply reliability is defined as the ability to satisfy the market demand and is determined by both supply-side and demand-side policy. To evaluate the gas supply reliability of the natural gas pipeline system, we have applied the method of gas supply capacity calculation based on the results of the previous gas supply reliability studies. The method combines the unsteady flow hydraulic analysis, simulation of the state transition process, and the forecasting analysis of the demand and consumption. The analysis presents a case study based on the gas pipeline system in China. The analysis results indicate that the COVID-19 consequences will cause a decrease in gas supply reliability.