Abstract: Reservoirs from the braided fluvial sandstone is loose with gravel, the porosity-permeability relation is poor and the relationship between the microscopical characteristics and the production capacity is complicated. By taking Jinzhou oilfield in Liaodong bay of Bohai sea as example, using the core testing data, the well logging data and the DST data, the quantitative discriminant criteria were established to subdivide the lithologic reservoir into three types: conventional sandstone, gravelbearing sandstone and sandy conglomerate. And then micro-characteristics of different lithologic reservoir such as grain size sorting, porosity structure, shale content and the difference of clay minerals were studied. On this basis, the effects of different micro-characteristics on the production capacity of each type of reservoir were studied, and the relationship between grain size sorting, porosity structure, shale content, clay minerals and the production capacity were discovered.