Abstract: The fluctuating gas consumption or peak and/or trough gas consumption always exists in the gas supply terminal, the gas supply regularity during month, day and hour results in a inequality. However, the inequality between the gas supply from gasfield and gas consumption can be equilibrated by a transient analysis method with a mathematical model, the method can accurately describes the dynamic operating process of gas transmission pipeline, analyzes the change regularity of pressure and flow rate at every hour interval and check up the gas inventory. The calculating results is more accurate than the static approximation method. Taking Ha-Yi gas pipeline applied the gas inventory and peak shaving technique as an example, the selection method of initial condition in the transient analysis is given.