The error of commercial Fiber Optic Current Transducer(FOCT) must be less than 0.2%, the sensing head is a key factor for high-accuracy current sensing. The topology, operational principle and difficulties of fiber optic current transducer were introduced, and the sensing head affecting the performance of fiber optic current transducer was analyzed. The design, fabrication and encapsulation of sensing head were studied. The improved sensing head that can avoid all kinds of negative effects was manufactured by using suitable material and method, which has excellent environment adaptability, reliability and stability. The experimental results show that the measurement precision of fiber optic current transducer is improved by using the improved sensing head, and the FOCT can satisfy the accuracy requirements of the 0.2 S class measuring electronic transducer, meeting the requirements of digital substation.