Electric pulse current (EPC) was employed to treat ZA27 alloy cast in the sand mould during the solidification. The experiment results indicated that the shrinkage cavity and the porosity in the ZA27 alloy was apparently reduced. And correspondingly, the mechanical properties of the castings were certainly improved. The current pulse applied in the initial stage of the solidification produced a better treatment result. The density of the casting ZA27 alloy treated with EPC in initial stage and later stage increased by 4.1 and 1.6 percent than that without EPC, respectively.