The main objective of this study is to determine the influence of mold casting variations and annealing process of CuZn cast alloy. The CuZn cast alloy was annealed at 400 C to 2 hours. Failure time measurement was conducted by using Torsee's Torsion Repeated and Bending Fatigue Machine with only one level of loading 3º. Microstructure analysis performed by using Optical microscope to analyze its correlation with hardness value of CuZn cast alloy. Fracture Phenomenon of fracture fatigue specimen was analyses by using SEM.The reduction in fatigue toughness accompanied by the increase in ductility in CuZn cast alloy after annealing treatment.The decrease in mechanical properties also shown by the reduction of hardness value confirmed by changes size of its dendrite arm spacing.The results of the investigation revealed. The results showed a significant influence of the annealing process and mold variations on the failure time and mechanical properties of CuZn cast alloy.