The invention belongs to the technical field of multilayer ceramic capacitor materials, in particular to a high-temperature X8R type ceramic capacitor dielectric material and a preparation method thereof. This kind of high-temperature X8R ceramic capacitor dielectric material is based on the eutectic of barium titanate and bismuth sodium barium titanate, and the eutectic of oxides of niobium, manganese and A, silicon lithium eutectic, and boron barium are added. Fusion, Re 2 o 3 , wherein the element A is one or more of cobalt, nickel, zinc, bismuth, etc., and the element Re is one or more of rare earth elements such as praseodymium, samarium, gadolinium, neodymium, and dysprosium. The capacitor made by using the high-temperature X8R type ceramic capacitor dielectric material of the present invention has high dielectric constant, high compressive strength, high temperature stability, and can be combined with medium-low temperature sintered 30Pd-70Ag inner when preparing multilayer ceramic fixed capacitor The electrodes are matched to achieve medium-temperature sintering, and realize the application in high-temperature environment, which has high industrialization prospect and industrial application value.