Half coated metal core piezoelectric fiber can harvest environment vibration energy through bending displacement. The electromechanical coupling dynamics model of half coated metal core piezoelectric fiber is established by analytical mechanics method.The analytical expressions of normalized harvest power after AC DC transfer excited by harmonic force is derived.The power harvest efficiency affected by radius ratio,flexibility coefficient ratio of metal and piezoelectric material,electromechanical coupling coefficient and direction of excited force is investigated.The results shows while radius ratio reach 2.4 or material electromechanical coupling coefficient reach 0.4,the power harvest efficiency is near the optimized value. The results can be used to design and optimize the piezoelectric fiber for power harvesting.