The invention provides a twinkling transparent ceramics with garnet structure and a preparation method thereof. The twinkling transparent ceramics is characterized in that oxysalt of the garnet structure is taken as substrate, and the structural formula of the garnet structure is 3mR, 3nR': (A(1-m-n-x) A'x)3 (By C(1-y))5 O12, wherein, m and n are more then or equal to 0 and less than or equal to 0.1, x is more than or equal to 0 and less than or equal to 1, and y is more then or equal to 0 and less than or equal to 0.4; one or combination in Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Cr, Ti and Mn can be taken as luminous ion. The product uses high-purity material (being more than 99.99%) for high-energy ball milling to process powder by being added with sintering accessory ingredient and combining vacuum sintering, so that the twinkling transparent ceramics with high optical quality can be obtained. In visible light area, the twinkling transparent ceramics has the transmission reaching 80% or above, and the stimulated emission peak is matched with sensitizing range of a photoelectric detector. The twinkling transparent ceramics is a scintillating material having application prospect in the field of detecting high-energy rays (such as electron, alpha and beta particles, x-ray, gamma-ray and the like). The invention can be applied to an electron microscope, a counter, a ray imaging screen and the like, and has the advantages of simple technique, low production cost, etc.