The microwave dielectric ceramic Li9Zr3NbO13 was found and investigated. Prepared via the solid-state reaction method, the Li9Zr3NbO13 formed as a Li2ZrO3-type solid solution at 880-900 degrees C, with monoclinic structure in C2/c space group and Z = 4. Typically, the Li9Zr3NbO13 sintered at 900 degrees C exhibited the excellent microwave dielectric properties of epsilon(r) = 21.3, Qxf = 43 600 GHz (at 7.4 GHz), (f) = 7.3 ppm/degrees C.