A photoelectric hybrid coupling current transformer has a lot of obvious advantages over a traditional electromagnetic current transformer. It is very valuable in practical application for the electricity protection and signal measurement of power system. This paper will introduce the design of a new type of Rogowski coil, integral and filter circuit, the realization of A / D timing and Manchester decoding with CPLD. The test results have proven that the proposed system design can perform the expected functionality of photoelectric coupling current transformer. It can better meet the power system’s requirements in the high-speed data processing, large data quantity and complex operation. It also has merit of being simple in structure and easier for modification. It is worth of further investigation.