The theoretical model of the hexagonal fiber array is established based on Fraunhofer diffraction theory. The far field distribution of the hexagonal fiber array is presented. Energy contained in the central lobe and Strehl ratio are taken as the two evaluation parameters of coherent combined system. The effects of arrangement, amplitude，filling factor and phase errors on far field distribution are analyzed and simulated. A seven-element hexagonal fiber array with a hexagonal prism is experimentally constructed. The hill climbing method is employed to detect and lock the element phase. The filling factor of the coherent array achieves 066. The combined beam of Strehl ratio of 070 and energy contained in the central lobe of 040 is experimentally obtained. And the energy contained in the central lobe of two-element linear array and four-element square array are 045 and 018, respectively.