A novel voltage real-time sampling correcting method is proposed for the real-time sampling of discharge and charge process of Lithium-ion battery (LIB) packs, which is aiming to solve the line voltage drop compensation problem of non-four-wire LIB packs. In this method, the midline drop mechanism of LIB charge and discharge process is analyzed and the impact of different combinations of charge and discharge status on the sampling is studied, which is aiming to achieve effective voltage signal real-time monitoring of LIB packs. Experimental results show that, in the work status voltage sampling process, this method can effectively solve the non-four-wire LIB pack voltage sampling problem. The difference between the actual voltage and the sampling voltage of LIB cells is within 5 mV. The proposed non-four-wire cable drop compensation method can effectively solve the accurate real-time sampling problem of LIB packs, which can characterize the actual working conditions accurately.