ZrB2-SiC composites with different additives were prepared by spark plasma sintering (SPS). Taguchi design was applied to explore effective parameters for achieving the highest hardness. Nine factors including contents of SiC, C-f, MoSi2, HfB2 and ZrC, milling time of C-f (M.t) and SPS parameters such as temperature, time and pressure in four levels were considered through the Taguchi technique. It has been concluded that the most significant effects on the hardness are related to temperature, MoSi2, ZrC, SiC and HfB2 by 54.7%, 12.3%, 9.1%, 8.2% and 6.7%, relative importance respectively. Pressure by 0.13% and C-f by 0.43%, M.t by 0.94 and time by 2% have the least effect on the hardness. (C) 2015 Elsevier B.V. All rights reserved.