In this article, a simultaneous measurement system of space charge and current as well as space charge and the potential in open circuit based on the “ region division but at the same time” measurement strategy is proposed to obtain the dielectric response information comprehensively and to accurately characterize the dielectric properties of solid dielectrics. The simultaneous measurement system consists of the readymade current measurement unit, potential measurement unit and space charge measurement unit. Those measurement units are reasonably combined through a T-filter and an inductance to isolate alternating component to ensure that there is no mutual interference between each unit during the measurement process. In this way, the simultaneous measurement of the current, space charge and the potential in open circuit could be achieved. The measurement system is validated by the measurement results of the current, potential, and space charge of low-density polyethylene (LDPE) samples with silicon carbide (SiC) filler. Results show that the basic noise of current measurement is quantitative in pA, the voltage measurement is good in the range of 1 ~ 10 kV, and the accuracy of space charge measurement is not affected. The proposed simultaneous measurement system is simple and easy to achieve technically, which can realize simultaneous measurement of current, potential, and space charges of solid dielectrics. In addition, the combined simultaneous measurement system still has room for further expansion and provides reference and basis for combined simultaneous application of multiple measurement technologies.