The invention relates to a storage battery. A trapezoidal balance storage battery comprises a shell, a positive terminal, a negative terminal, a valve hole, a positive pole plate, negative pole plates, paper blocking plates and bus bars, wherein the positive terminal, the negative terminal and the valve hole are arranged on the shell; the positive pole plate, the negative pole plates, the paper blocking plates and the bus bars are arranged in the shell; the cross section areas of the positive pole plate and the negative pole plates are decreased gradually from top to bottom. The plate widths of the pole plates on the upper part of the storage battery provided by the invention are more than that of the pole pates at the lower part, and the thicknesses of the pole plates on the upper part of the storage battery are more than that of the pole pates at the lower part, so that the utilization ratio of the lower end is just matched with that of the upper end; because the widths of the pole plates at the upper end are increased, the baffles are also increased; because the pole plates at the upper end are thicker, a great amount of electrolyte is required in reaction, and the baffles at the upper end are thicker than that at the lower end; because the volumes of the pole plates at the upper end are large, the generated electricity quantity is great, the baffles at the upper end are thicker, the voltage drop of the positive electrode and the negative electrode can be insulated effectively, and circuit disconnection can be prevented effectively; the balance utilization ratio of the storage battery is improved greatly; the up-down balance property is improved.