The invention discloses a preparation process of a gradient high-purity melted quartz crucible. The preparation process comprises: carrying out ball milling on a high-purity melted quartz slurry and common-purity melted quartz slurry according to the same process in different containers; adding high-purity melted quartz particles and common-purity melted quartz particles respectively to prepare melted quartz slurry capable of being used for pouring, wherein the high-purity melted quartz particles and the common-purity melted quartz particles have the same grain diameter distribution; putting one layer of organic separation membrane into a pouring mold, and controlling the shape and position of the separation membrane through a detachable framework, so as to determine the ratio of inner and outer grouting spaces of the mold; injecting the high-purity melted quartz slurry and the common-purity melted quartz slurry into the mold on an inner layer and an outer layer of the separation membrane; drying or carrying out thermal initiated curing to enable a crucible blank to have strength; and polishing and revising the molded crucible blank, and then putting the crucible blank into a kiln for sintering and the like. By adopting the preparation process of the gradient high-purity melted quartz crucible, pollution to polycrystalline silicon by the quartz crucible can be avoided and the crystallization rate of the crucible in an ingot casting process is reduced.