The present invention relates to the field of oil extraction engineering. Disclosed are an electric machine driving method and system for a non-conventional work mechanism of an oil extractor. The method proposes using a power frequency drive technique for a complete crank cycle, and using a variable-frequency drive technique for an incomplete crank cycle in an extraction operation and for an incomplete crank cycle in a non-extractive operation. The system is provided with a power frequency circuit and variable-frequency circuit with a common input and common output. An input terminal of the power frequency circuit and variable-frequency circuit is connected to the power frequency power supply circuit, while an output terminal is connected to the driving motor of the oil extractor. A variable-frequency circuit is provided with a variable-frequency drive. The power frequency circuit and variable-frequency circuit are further provided with an operation control unit. The method and system provide a means for driving a motor under a non-conventional work mechanism. When an actual production stroke requirement is not equal to the power frequency stroke, the method and system can also reduce actual operating time of the variable-frequency drive, lower an operating strength of the variable-frequency drive, effectively improve a heat dissipation condition of the variable-frequency drive, and extend the service life of the variable-frequency drive.