In this work, 3-D nanoscale line patterns were fabricated on SU-8 layers by Ga+ focused ion beam (FIB) lithography and used as Nanoimprint lithography (NIL) mold. Both V-shape side wall and opposing dose deficiency effect were observed and analyzed during the FIB milling process. Different beam currents were utilized to fabricate SU-8 pattern and it is found that the lower beam currents provide higher quality pattern with smooth edges and straight side walls. In addition, the impact of crosslink density of SU-8 material on the FIB milling efficiency was discussed. Both thermal and ultraviolet (UV) NIL were conducted using these line patterns to study the deformation of SU-8 mold and filling ratio of imprinting material. The experiments revealed that the imprint pressure and physic properties of imprinting material are the most critical factors in these NIL processes.