The invention relates to an automatic dissolving device for production of casein. The automatic dissolving device comprises an inspection part, a control part and an execution part, wherein the inspection part feeds back an electric signal to a PLC automatic control module via a pH electrode, the control part transmits the electric signal to the execution part (a material pump, an alkali pump and an alkali valve), the alkali pump works, an alkali inlet valve is opened, a small amount of alkali lye is added, so a dissolving pH value is controlled; the dissolving pH value is stabilized through continuous monitoring and feedback, so finally, production efficiency is improved, and casein product quality is stabilized.