Gillespite-type SrCu0.95B0.05(B2+:Cu,Co,Mn,Ni,Mg,Zn)Si4O10 (SCBS) ceramics were prepared by high-temperature solid-state method. Their microwave dielectric properties and crystal structure evolution were studied by P–V-L theory, bond valence model, and X-ray photoelectron spectroscopy. Varying B2+ ion changed ionic polarizability and bond ionicity, causing dielectric constant εr of SCBS to change. The change in quality factor Q × f was explained by lattice energy, oxidation state of Cu, and internal strain/fluctuation. The temperature coefficient of resonator frequency τf was regulated by B–O bond length and valence. The optimal microwave dielectric properties were exhibited by SrCu0.95Mn0.05Si4O10 after sintering at 1050 °C: εr∼5.8 ± 0.03, Q × f∼65,589 ± 2611 GHz (@15.8 GHz), and τf ∼ -50 ± 4 ppm/°C. These materials show great potential application prospects for 5G/6G wireless communication.