The end fire coupling between the single-mode optical fiber and the Ti-diffused LiNbO3 single-mode planar optical waveguide has been studied. Here we report our measurements of the field intensity distribution and the experimental results of coupling efficiencies under the influence of various alignment tolerances. Using a photoresist to produce a microlens directly at the end of a fiber. The Gaussian waist diameter of the fiber output is reduced and the coupling efficiency has been improved by 1.47 times, which is conformable with the theoretical values.