The utility model discloses an automatic control device for nickel carbonate preparation in a nickel electrolysis purification process. The automatic control device comprises a sodium carbonate flow adjustment device, a copper tailings flow adjustment device, a pH (power of hydrogen) detection device, an arithmetic unit and a PID (proportion integration differentiation) controller, wherein the pH detection device is connected with the arithmetic unit; the sodium carbonate flow adjustment device, the copper tailings flow adjustment device and the arithmetic unit are connected with the PID controller; the sodium carbonate flow adjustment device is arranged on a sodium carbonate liquid inlet pipeline; and the copper tailings flow adjustment device is arranged on a copper tailings liquid inlet pipeline. According to the automatic control device, the PID controller sends a control execution command to the sodium carbonate flow adjustment device and the copper tailings flow adjustment device, the pH detection device feeds back a signal to the PID controller, and then the PID controller sends a control command to further adjust and control, so that full automatic control of the nickel carbonate preparation is achieved, a pH value and the concentration of nickel carbonate can be controlled stably, and resource waste in a nickel carbonate preparation process is reduced.