A method and an apparatus for transmitting frame data between a near-end device and a remote device are provided. The method includes: generating, by the near-end device, a base frame in a user-defined frame format, wherein a PHY converting chip is built in the near-end device, the base frame includes a first number of super groups, each super group includes a second number of base groups, and each base group includes media access control (MAC) frame structure data and an interframe gap; matching duration of the MAC frame structure data and the interframe gap with an output timing sequence of the PHY converting chip; and converting the base frame into an optical fiber signal through the PHY converting chip, and sending the optical fiber signal to the remote device.