We have recently shown that patterns with $30\mathrm{nm}$ line width and micrometer scale periodicity could be steadily fabricated by employing localized surface plasmons lithography based on a soft mold [ Opt. Lett. 35, 13 (2009)]. In this paper, the dependence of the resolution (pattern periodicity), critical dimension, and electric field intensity on the geometrical parameters of the soft mold, such as ridge width, mold periodicity, ridge depth, and slope, have been systematically studied and analyzed. The relevant simulation results by finite-difference time-domain demonstrate that the critical dimension exhibits a perfect stabilization and the value of electric field intensity would be especially large, when the ridge depth is in the range from 100 to $270\mathrm{nm}$ and the slope angle is below $35°$ . Importantly, the optimal resolution and critical dimension can reach 100 and $17\mathrm{nm}$ , respectively, by reasonably designing the corresponding mold periodicity and ridge width, which indicates that the method is particularly suitable for obtaining patterns with high density and is extremely promising for bio-sensing and photonic crystals application.