A dianhydride and a polyimide formed by the same are provided. The dianhydride has a chemical structure represented below: wherein Ar is a fluorene-containing group. The dianhydride can be polymerized with a diamine to form a polyimide with a repeating unit of a chemical formula: wherein Ar is the fluorene-containing group, and n is a positive integer from 1 to 5. The polyimide simultaneously has excellent thermal stability and hot workability, and can therefore be applied in several industries.