Fiber-lighting attracts widespread attention because of its advantages of low cost, high safety, good portability and easy decoration. However, the problem of low flux efficiency of coupler products is still difficult to be solved because of the big divergence angle of light sources. In order to improve the efficiency, a coupler based on total reflection theory is designed and fabricated. And according to the results of experiment, the coupler has strong light focusing ability, high coupling efficiency and reduced size. It is a good way to increase the efficiency of light emitting diode (LED)-fiber coupling.