The black strata are widely distributed and have special properties. Selecting the black strata of I.ower Cambrian Zhalagou Formation in South Guizhou to be the object of study, this paper determines the weathering stage of black strata by the characteristics of the minerals and chemical composition of the black strata in the weathering, and simulates the chemism of water and rock by immersion test and water quality analysis test to provide the reference for the future study. The findings indicate that the chemical weathering of the black strata has been completed the stage to remove Na and Ca and enters into the middle stage to remove K. The black strata involves more complex chemical processes in the water and rock chemism, gradually forms stable clay minerals and secondary minerals by the dissolution, hydrolysis, and hydration.