In this study, simulation aided design of grinding circuit for a gold mine in Iran is presented. The main parameters for the design of the grinding circuit are the ore specifications and the considered operating conditions. Ore specifications were characterized by grinding tests, which included the Drop - weigh test (A, b), the abrasion test (t(a)) and the Bond Work Index test (W-i). For this study, the operating conditions for the processing plant are the ability to process clayey minerals and the plant throughput and the d(80) of the hydrocyclone overflow (leaching tank feed), which are 125 tons per hour and 45 mu m, respectively. Simulation operations were performed using grinding parameters (A, b, t(a), W-j) operating constraints (plant capacity, d(80) of the hydrocyclone overflow and ability to work for clayey minerals), existing mathematical models for different types of crushers, mills and separators and JKSimMet software. By completing the simulation process, three different alternatives for the grinding circuit of the considered ore were predicted. These three alternatives have been compared and evaluated with each other in terms of specific energy consumption (kWhlt), sensitivity to operational variables and the ability to process clayey minerals. The optimal circuit must have the capability to process clayey minerals and must have the lowest specific energy consumption and the least sensitivity to operational variables. By considering all these factors, the Alternative 3 is selected and suggested for an efficient grinding circuit.