This paper introduces the efficient three-dimensional (3D) simulation of thick SU-8 structures realized by single-step projection lithography. Profiles of 3D structures obtained by this lithography method depends on two process parameters: (i) The exposure dose and (ii) the focus depth. For fabricating complex 3D structures used in microfluidics or bio-engineering tools, the resulting geometries depending of these two process parameters should be predicted before processing. Although several lithography simulation methods have been developed for SU-8 processing, the existing models are unsuited for single-step projection lithography technique. This paper described how the simulation process have been developed and successfully tested on a specific design of honeycomb structures. Through the various experiments, simulation results revealed similar dependence on two process parameters, and the validity of simulation algorithm was therefore confirmed.