Embodiments of the present application provide an optical line terminal line card and a method compatible with a PON function. The optical line terminal line card includes an optical module, a MAC module, a toggle switch, a switch controller, a series resistor and a pull-down resistor. The optical module is connected to the MAC module to form a first connection line, the series resistor is provided on a side of the first connection line close to the optical module and on the first connection line, the pull-down resistor is connected to the first connection line by means of a second connection line, the toggle switch is provided on the second connection line and is located between the first connection line and the pull-down resistor, and the switch controller is connected to the optical module and the toggle switch, respectively.