To improve the performance of image transmission systems on optical electronic theodolites, the Rocket IO IP core based on a Field Programming Gate Array(FPGA) is designed to accomplish the interfaces conversion between parallel camera link and serial optical module.It uses a custom image transmission protocol to build a platform to interconnects the image transmission system with various subsystems. Using this optical fiber transmission channel,the system realizes high-speed real-time image transmmision down to a machine for processing, displaying and recording. It can also compound and transmit commands and synchronization timing up to the camera. This paper describes the system architecture, the software and hardware design for the sender, and receiver, and the key technologies for the system, and introduces attributes of Rocket IO, transceiver state machines for data-packets and the image transmission protocol. The experimental results indicate that the system will operate at a rate up 2.5 Gb/s, the transmission link is stable, reliable with no error codes. As the protocol is open-source, users can use the serial data directly.This design breaks through the limitations of traditional optical fiber transmission protocol, and reduces the amount of wiring. The advantages of this system is high bandwidth, high quality images and high anti-jamming level.After a validation test, the system has been applied to various projects.