The changing trends of Ba4Nd9.33Ti17.5-xSn0.5MxO54 (BNST-xM) ceramic dielectric properties and microstructure were investigated by substituting two types of metal ions M (M = Mn, Mg) for Ti4+ at B-site. X-ray diffractometer (XRD) results show that M2+ are successfully formed as a single tungsten-bronze type structured phase, except that x is equal to 1.25. It can be seen from the scanning electron microscope (SEM) that the rise of the ion doping amount gradually increases the defects, and the crystal shape gradually changes from slender columnar to short and rounded. M2+ substitutions greatly impacted the suppression of oxygen vacancies and Ti3+ generation in BNST-xM ceramic, particularly Mg2+, which was confirmed by X-ray photoelectron spectrometer (XPS) results. The incorporation of M2+ ions into the system increased the Q·f value while reducing the dielectric constant of the ceramics. Mg2+ can improve the material's Q·f value, and the doping of Mn2+ will lessen the frequency temperature coefficient of the material more. When the doping amount x of Mg2+ was 0.25, the system had the best dielectric properties: ε = 64.4, Q·f value = 10,170 GHz, and τ = 25 ppm/°C.