A multiple-frequency inversion method and a control apparatus for an internal combustion engine driven generator includes an inverter unit that employs a multiple-frequency inversion technology, controlling the inverter unit through a low switching frequency f to obtain a 2f modulated frequency, thus resolving the problem that a low frequency switching component generates a high frequency modulated waveform. Four switching devices in the inverter unit have the same working frequency, alleviating the controller load. In addition, a high modulated frequency reduces the device parameters of the filter unit, resulting in a smaller-sized and lighter apparatus, thus giving the generator portability. Reduction of the device parameters of the filter unit means reduction of the output internal resistance of the generator, therefore increasing the non-linear load capability of the generator.