In this paper, the transport characteristics of the electrons in the double-barrier heterostructure under adding periodic positive and negative bias ("rocked" ratchet) are numerically simulated by the transfer matrix method. The expressions of net current and net heat flow between the two electronic reservoirs are obtained. Further, the performance characteristics of net current, net heat flow and coefficient of performance are analyzed. The results obtained here may provide some significant guidance for the design and manufacture of mecro-thermoelectric devices.