Graphene has excellent conductivity and mechanical property, and simonkolleite is a good semiconductor. To make use of the advantages of the both, a composite made of graphene and simonkolleite was synthesized by mechanochemical method at room temperature, and its electrochemical performance was analyzed. Cycle-voltammetry and constant current charge and discharge tests demonstrate that the maximum specific capacity is 30.5 F/g when the scan rate is 5 mV/s. The polarization may appear if the scan rate reaches 80 mV/s, resulting in the peak value of the specific capacitance. The time for charge and discharge is the longest with the current density of 0.1 A/g, and the cycle performance is also rather good.