The bentonite deposit in Lijia area, Guangfeng County, Jiangxi Province, is mainly occurred at the top and bottom of the second lithological layer of acid volcanic rocks which used to be defined as Nanxiong group, Upper Cretaceous. The main mineral composition of bentonite is montmorillonite, the texture and structure of ores are related with primary rocks. The chemical composition of ores is similar to that of acid lava, the shape and space distribution of the orebodies are controlled by acid lava flow facies belt. It is believed that the mineralized primary rocks are acid glassy lavas experienced hydrolyze devitrification to cause the formation of the bentonite deposit, thus, the genetic type of the deposit should be regarded as the weathering and leaching altered rock type.