The effect of mixed grinding of Y2O3, BaCO3 and CuO Powders using a planetary ball mill before eat treatment of the crystal structure and the superconducting properties of the sintered body has been investigated by XRD, SEM, TEM-EDX, EELS, and measurement of the critical temperature and critical current density. The size reduction of powders predominates in the early stage of grinding, after which aggregation of the obtained fine particles takes place. The homogeneity in the mixture is improved with increase in grinding time. The critical current density of the sintered body changes with increase in grinding time of the mixture and reaches maximum value at 60 minutes grinding, while the critical temperature is almost independent of grinding time.