There were two important techniques for casting bronze coins in Han Dynasty: stack-casting and bunch-casting. A number of factors can influence the casting process. By virtually changing any of these parameters, computer simulation could help to analyze the effects of different factors on the casting process. In this research, the computer simulated casting processes were used to study how the mold materials influence the mold filling capacity during bunch-casting and how the processes of mold filling during stack-casting and bunch-casting differ. The results indicated that 1) when using the same casting mold (a clay mold), stack-casting shows better sequential filling than bunch-casting does, and therefore, has a higher rate of finished coins; 2) different molding materials, e.g., stone, metal and clay, affect the filling process greatly. Good heat preservation and a higher preheating temperature are desired properties of the mold. The clay mold is the best, and metal ones are better than the stone molds. A combination metal-clay mold is better than a metal-metal mold.