To solve the bottleneck problem of high-speed, high-resolution real-time image transmission and processing on photoelectric theodolite, a framework of real-time image transmission based on optical fiber and FPGA + multi-core DSP processing unit is proposed, which means this design realized high-speed image transmit to multi-core DSP processing unit in real time. On this basis of that, a custom protocol of image transmission on optical fiber has been developed by using the protocol to interconnect image processing unit between various subsystems, such as displaying subsystem and recording subsystem. A collectivity design of system, hardware design and software design of system are described, especially designs of image transmission protocol and multi-core DSP processing unit, which are introduced in detail to build an experimental platform, test and analyze the system. Extensive experiments on the whole system validate that, real-time image transmission to subsystems gets rate at 2.5 Gb/s by optical fiber channel, and transmission gets rate at 3.125 Gb/s between the multi-core DSP and FPGA on multi-core DSP image processing unit. The system is stable, reliable and low error rate. It has advantages such as strong processing capacity, strong performance of anti-electromagnetism interference. This system has been applied in engineering projects.