An effective radially polarized beam can be generated by coherently combined beams, each one with an appropriately oriented linear polarization, named radially polarized coherent beams array. However, the characteristic of the effective radially polarized beam is different from that of an ideal one. Based on the Richards-Wolf vector diffraction theory, numerical calculation is performed to analyze the intensity distribution at focal plane of a tightly focused radially polarized coherent beams array. The parameter, such as the full-width at half-maximum (FWHM) of the longitudinal and total field, the purity parameter and the generation efficiency of the longitudinal field are used to characterize the intensity distribution at focal plane. The results show that the azimuthally polarized field exists at focal plane for a tightly focused radially polarized coherent beams array, in contrast with an ideal radially polarized beam. To generate a radially polarized beam with better beam quality, the beamlets should be placed in one single ring and close to the pupil edge of the objective lens. When increasing the number of beams in the single-ring-shaped array, the FWHM of the longitudinal and total field and the purity parameter remain almost unchanged, but the generation efficiency of the longitudinal field is improved.