Provided is a negative photoresist used for a semiconductor encapsulation process, belonging to the technical field of semiconductor processing. A negative photoresist formulation includes 40-65 wt % of modified epoxy acrylate, 3-6 wt % of photosensitizer, 100-1000 ppm of leveling agent, and the remainder of solvent; the leveling agent is a solution of a 7:3 mass ratio of polydimethylsiloxane copolymer having a molecular weight of 3000-6000 and propylene glycol monomethyl ether acetate. If the negative photoresist is coated at a thickness of about 50 um, the coating uniformity can be controlled to below 5%, ensuring the quality of exposure such that the thickness of electroplated copper meets requirements.