The utility model relates to an automatic dissolving device for casein production. The automatic dissolving device comprises a static mixer (29), wherein the static mixer is connected with a variable frequency material pump (28) and a variable frequency alkali pump (13); a specially manufactured dissolving pipeline (32) comprises a pH (potential of hydrogen) electrode I (31), a hot water tank (33), a pH electrode II (34) and a pH electrode III (35); the pH electrode I (31) is connected behind the static mixer; the pH electrode II (34) and the pH electrode III (35) are connected to the one-third position and the two-third position of the specially manufactured dissolving pipeline (32) respectively; the specially manufactured dissolving pipeline is arranged in the hot water tank (33) and can keep a constant dissolving temperature; an alkali liquid inlet I (36) is connected behind the pH electrode II (34); an alkali liquid inlet II (38) is connected in front of the pH electrode III (35); an electromagnetic valve I (37) is connected in front of the alkali liquid inlet I (36); an electromagnetic valve II (39) is connected in front of the alkali liquid inlet II (38); a secondary dissolving pipeline (41) and a one-way valve (42) are connected behind the specially manufactured dissolving pipeline; and the pH electrodes on the pipeline are connected with a PLC(programmable logic controller) automatic control module (40).