The utility model discloses an air compressor machine frequency conversion constant voltage gas supply system, include frequency conversion cabinet, the power frequency cabinet be connected with the air compressor machine, be connected with the gas holder on the gas transmission pipeline of air compressor machine output and be used for detecting air feed pressure signal's pressure sensor, frequency conversion cabinet, power frequency cabinet are connected through switching over the control unit and pneumatics electromechanics, it includes that the controller reaches the change over switch rather than control connection to switch the control unit, the controller is arranged in detecting the break -make of the fault -signal of frequency conversion cabinet converter with control change over switch. The utility model discloses an air compressor machine frequency conversion constant voltage gas supply system adopt to switch the switching that the control unit realized frequency conversion and power frequency mode, should switch the control unit and detect the fault -signal of converter in the frequency conversion cabinet with control change over switch's break -make through the controller, and its operational reliability is high.