A digital ac constant current source uses the adjusting method with two stages of pressure and current, and a controller shows the adjusting result. The structure of the utility model comprises a primary regulation regulator, a secondary regulation regulator, an output transformer, a pressure sensor, a current sensor, a first and a second motor and the controller. The terminals of the first and the second motors are respectively connected with the mcu in the controlling circuit, and the output shaft of the mcu respectively contacts with the carbon brush mechanism at the tapping parts of the primary and secondary regulation regulator, and the two ends of the primary regulation regulator are the input ends. The tapping part is connected with one end of the secondary regulation regulator, and is connected with the pressure sensor. Another end of the secondary regulation regulator is series connected with an inductance coil to reach the ground, and tapping part of the secondary regulation regulator reaches the output transformer positive degree through a switch. The secondary output transformer is series connected with the current sensor and then connected with the loading resistance. The utility model can be adjusted automatically to output the current.