The invention discloses a pH controller automatic calibration device and a calibration method thereof. The existing pH controllers are all manually assembled, wired and calibrated with low efficiencyand high error rate. The pH controller automatic calibration device provided by the invention comprises a touch screen, a calibration module, a calibrator and an offline burner. The calibration modulecomprises a central processing circuit, a power supply voltage regulator circuit, a standard voltage switching circuit, a pH controller power supply circuit, a pH controller communication circuit, acalibrator communication circuit, a touch screen communication circuit and pH controller switching circuits. Each pH controller switching circuit comprises a voltage control circuit, a current controlcircuit, a burner control circuit and a pH controller communication control circuit. The total number of pH controller switching circuits is n. According to the invention, the switching between the standard voltage output by the calibrator and the positive and negative connection of the voltage input end of a pH controller to be calibrated is realized through the combined action of two relays.