Zinc oxide powders were prepared by a complexation-precipitation method and characterized by XRD, SEM and BET. Their electrochemical capacities were tested by the charge-discharge method. The influences of some key preparative conditions such as the pH value of reaction solution and the content of aqueous ammonia on the performance of the ZnO samples have been studied by theoretical analysis and experimental investigation. The ZnO samples with high tapping density and electrochemical activity have been obtained under the optimum preparative conditions. The relation between the structure and electrochemical performance of zinc oxide was also discussed.