A novel Wilkinson power divider operating at arbitrary dual-frequency (namely dual band) with unequal power dividing ratio is proposed here. The asymmetric structure that consists of seven sections transmission lines with different characteristics impedances is given to satisfy the unequal and matching characteristic. To obtain the ideal isolation, a series resistor–inductor–capacitor (RLC) structure is applied. Furthermore, the closed-form design equations of the proposed dual-frequency power divider are derived based on circuit theory and ideal transmission line theory. Finally, calculation, simulation and measurement results of an example indicate that all the theoretical features of the unequal power divider can be fulfilled at the desired dual-frequency simultaneously.