The invention discloses a high breakdown field strength and energy storage density silicon dioxide doped cadmium copper titanate giant dielectric ceramic material and a preparation method. The ceramic material is prepared from materials shown in CdCu3Ti4O12-x wt%SiO2, wherein x ranges from 1.0 to 4.0, Cd(NO3)2.4H2O, Cu(NO3)2.3H2O and Ti(C4H9O)4 serve as raw materials, glacial acetic acid serves as a chelating agent, precursor powder is prepared through a sol-gel method firstly, the precursor powder is calcined at low temperature, CdCu3Ti4O12 ceramic powder which can be mixed on the molecular level and has good uniformity and high activity is obtained, then silicon dioxide powder is added into the ceramic powder, and the silicon dioxide doped cadmium copper titanate giant dielectric ceramic material can be obtained after ball milling, prilling, tableting, glue discharging and sintering. The ceramic material is simple in preparation method, low in reaction temperature, good in repeatability, high in yield and excellent in dielectric performance. The breakdown field strength can reach up to 895-2,353 V/cm, the energy storage density can reach up to 0.712-1.77 mJ/cm<3>, and wide application prospects are achieved.