Hollow fiber membrane is to separate different component gases according to different mass transfer rates of each component in the mixed gas driven by the partial pressure difference through the membrane. Its separation performance is related to the flow pattern， gas feed mode and altitude. An all-purpose mathematical model of hollow fiber membrane was developed for different flow paths and experimentally verified. Then， the relationships of nitrogen purity， pressure resistance， permeability and so on with altitude were obtained in the process of membrane separation. Furthermore， the influence of different flow paths on the process of membrane separation was analyzed. Results show that， at bore-side gas feed mode， the nitrogen purity of counter-current flow is higher than that of co-current flow， while the difference between the two types increases first and then decreases with altitude. In counter-current flow， the nitrogen purity of bore side is higher than that of shell side and the separation performance is better. At low-altitude， the flow pattern has greater influence on the performance of hollow fiber membrane for on-board inerting gas generating system； At high altitude， the gas feed mode has greater influence on the performance of hollow fiber membrane for on-board inerting gas generating system.