In this work, (20-x)MgO-20Al2O3-56SiO2-4B2O3-xCuO (x = 0, 0.25, 0.5, 0.75, 1, 1.25 mol%) glass-ceramics were synthesized by solid-state reaction method. The crystallization, microstructure, thermal and dielectric properties of (20-x)MgO-20Al2O3-56SiO2-4B2O3-xCuO glass-ceramics was discussed in detail. It was demonstrated that the CuO lowers the crystallization temperature of alpha-cordierite and promotes the crystallization process of MgO-Al2O3-SiO-B2O3 glass-ceramics. Thus, the crystallization showed a substantial influence on the dielectric properties, as evidenced by an elevation in dielectric constant and a decrease in dielectric loss. Specifically, with the addition of 0.5 mol% CuO, the MgO-Al2O3-SiO-B2O3 glass-ceramics sintered at 1050 degrees C shows excellent properties of: er = 5.04, tand = 2.2 x 10-4, kappa = 3.4 W/mK and alpha = 1.75 x 10-6/degrees C. These works provide valuable insights into the design and development of (20-x)MgO-20Al2O3-56SiO2-4B2O3-xCuO glass-ceramics with tailored properties for structure/function integration in the electronics industry.