In nanoimprint lithography (NIL), one of the key points to be addressed is the printing uniformity on large area. During the process, the silicon mold undergoes significant mechanical stress of different kinds (tension, compression, flexion, and torsion). These stresses are function of the mold design and appear under the concurrent influence of both the applied pressure on the backside of the mold and an opposite force due to the polymer viscoelastic behavior. This translates into non-negligible deformations within patterned or unpatterned zones. This is a major issue because it causes nonuniformity of the printing, mold pattern break and degradation of the polymer surface. In this article, we demonstrate that during the imprint process mold deformations really occur at the local scale of the patterns but also at a larger scale.