The upside-down taper lens fiber end is produced by the special technique. This new type optical fiber end can be used to make varied optical devices. By using single-colour coherent light source and the second-order statistical correlation function, the optical field statistical correlation properties and the optical intensity distribution formed by the upside-down taper lens fiber end are calculated. The similar results of the general cut fiber end are given for comparison with the upside-down taper lens fiber end. The theroetical results are tested and verified using He-Ne laser as the single-colour coherent light source in experiment.