The invention provides a preparation method of an integral abnormally shaped transparent ceramic lamp tube; a sublimable or low-temperature meltable material is used as a core mold, a rubber material is used as an outer mold, a transparent alumina ceramic powder raw material after spray granulation fills a gap between an inner mold and the outer mold, then cold isostatic pressing molding is carried out, and a shape required by an integral ceramic lamp tube with the core mold is obtained; then the core mold material is sublimated or melted, and an integral abnormally shaped transparent ceramic lamp tube blank with capillaries at both ends remains; furthermore, the blank is deglued, biscuited and polished in an oxidizing atmosphere furnace and then put into a high temperature hydrogen furnace for sintering, and thus the fully dense integral abnormally shaped transparent ceramic lamp tube with high transmittance is obtained. Fewer organic matters are added in a granulation powder, the isostatic pressing molded blank density is relatively high, and relatively high transmittance can be obtained; at the same time, as the prepared lamp tube has no any lapped seams, the probability of generation of defects is reduced, exposed problems during lamp use are avoided, and the lamp life is relatively stable.