The present invention discloses an oil-displacing system and method. The system includes a power supply, a control switch, a controller and a transient electromagnetic generator. The power supply is connected to the transient electromagnetic generator, the control switch is disposed in a connection path between the power supply and the transient electromagnetic generator, and a control end of the control switch is connected to the controller. The controller is configured for controlling the closing and opening of the control switch, thereby controlling the connection and closing of the connection path between the power supply and the transient electromagnetic generator. The transient electromagnetic generator is disposed in an oil well casing at a position in an oil formation, for generating a transient electromagnetic field according to the connection and closing of the connection path between the power supply and the transient electromagnetic generator. The oil-displacing system and method provided by the present invention can dredge a pore throat and improve recovery efficiency.