The present invention provides a PWM current adjustment apparatus including a triangle wave generator (8) for generating a triangle wave voltage signal, a comparator (9), an FET (10), a power supply (14), a first resistor (11) and a second resistor (12). The triangle wave voltage signal generated by the triangle wave generator and a modulation signal provided by a modulation voltage source (13) are fed to the comparator, an output of the comparator is connected to a gate terminal of the FET, the power supply is connected to a source terminal of the FET through the first resistor, and a drain terminal of the FET outputs a driving current through the second resistor to a load.