Abstract: This paper discusses some problems of nonlinear porous flows in low permeability porous media, the properties of the porous flow fluid, and the selectivity of fluids in passing through porous media. Based on these characters, a new porous flow model, which can better describe low permeability reservoirs, is established. This model can describe various patterns of porous flows, as Darcy's linear law. All parameters involved in the model, with definite physical meanings, can be obtained directly from experiments.