Abstract: The effects of adsorption duration, adsorption pressure, column length and feed flowrate on the presure swing adsorption (PSA) process of the miniature separation of oxygen and nitrogen were simulated mathematically. The evolvement of the profil of oxygen concentration along the column was predicted. The simulating results show that the miniature PSA process is a kind of short-time cycles, and the higher the adsorption pressure, the longer the shock profile of oxygen concentration passes through the column. With the increasing of feed flowrate, the length of the column must be extended. It is founded that a short column will cause a decrease in oxygen purity in product and the cyclic steady-state is achieved after about 15 cycles. If the high purity oxygen is expected, the shock profile must not pass through the adsorption column. The mass transfer has important influence on the performance of the miniature PSA process and the local equilibrium approximation can not be applied.