A conductive base for illuminating building blocks has a base plate, an anode conductive component, and a cathode conductive component. The base plate further has a plurality of hollow studs. The anode conductive component and the cathode conductive component electrically connect to an external power supply. The anode conductive component and the cathode conductive component are projected out of recesses of the hollow studs to contact circuit boards of illuminating building blocks stacked on the base plate and then build electric connections. The neighboring illuminating building blocks stacked on the base plate can emit light together by the above base plate without intricate circuits.