A high-efficiency capillary-fiber optic probe is developed for measuring the concentration of trace elements. The optimal probe consists of an excitation fiber (incident fiber) and a ring of collection fibers which is made up of 6 fibers. Both simulation and experiment results show that the structure gives the higher coupling efficiency with a reasonable capillary diameter. The coupling efficiency of the probe is determined by the number and arrangement of the fibers, internal diameter and length of the fiber optic sensing probe, and the end reflectivity of the capillary. The concentration of the carbonic anhydrase solution and dezincification reagents also affect the efficiency. A fluorescence efficiency of 2.4% is obtained in zinc detection experiment.Central Universities (No.2010-Ia-020), and the Self-Determined and Innovative Research Funds of WUT (No.2012-Va-104).