The distribution of patterns of large alluvial rivers in China and the reason for their formation were analyzed based on remote sensing images, field survey data, hydrological data, and sediment data. Alluvial reaches of rivers in China are mainly meandering and braided reaches, while some local reaches are anabranching and anastomosing reaches. With the general and special characteristics of the distribution of river patterns taken into account, three critical factors are considered to be the main reasons for the formation of river patterns; the relative sediment transport rate(the ratio of the incoming sediment load to the sediment transport capacity), the relative riverbank erosion shear stress(the ratio of near-bank flow shear stress to the critical erosion-resistant shear stress of the river bank), and control of valley terrain(e. g. , the valley node and channel width).