The invention discloses an automatic attenuation control circuit employing PWM chopping constant-current control. The automatic attenuation control circuit comprises a logic control circuit, a comparator, a gate drive module, a current detection circuit, an H bridge output stage and an inductive load, wherein the logic control circuit comprises a core logic module, a self-attenuation control module and a time signal module; the core logic module is connected with the self-attenuation control module; the time signal module is connected with the self-attenuation control module; the self-attenuation control module is configured to convert a step signal and an output signal of the comparator into a control signal through an internal algorithm; and the control signal is output to the gate drive module through the time signal module. Automatic control on a current attenuation mode in a chopping constant-current working mode of a stepper motor is achieved; current fluctuation of the motor is reduced; stable operation of the motor is optimized; noise of the motor is reduced; meanwhile, the rotating speed of the motor is improved; and the automatic attenuation control circuit is suitable for being applied to a high-speed and high-precision motor drive circuit.