In order to improve the fuel economy of hybrid electric vehicles, a novel plug-in power-reflux hybrid electric vehicle powertrain equipped with an electromechanical control continuously variable transmission (EMCVT) is proposed in this study. The proposed structure, which combines the dynamic property of the planetary mechanism and regulating characteristics of the continuous speed ratio with EMCVT, can transmit power in two modes, namely power-reflux mode and pure-CVT mode, thus realizing the multistage design of the overall transmission system. Hence, it demonstrates a wider speed ratio variation range and higher transmission efficiency than the "Pathfinder-like" parallel configuration with traditional electro-hydraulic CVT (EHCVT). To take full advantage of its potential for fuel economy, the highest transmission efficiency of the system is taken as the optimization objective for the target speed ratio of the system. The optimization results are incorporated in the control strategy based on Pontryagin's minimum principle to simulate fuel consumption under the new European driving cycle (NEDC), highway fuel economy test (HWFET), and urban dynamometer driving schedule (UDDS). Compared with the simulation of the "THS II-like" configuration with similar vehicular parameters, the results show that the novel configuration has better fuel economy.