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The present invention relates to the technical field of high-temperature energy storage dielectric films, and discloses a preparation method of a porphyrin cross-linker modified polyimide high-temperature energy storage dielectric film. Polyamic acid (PAA) precursor is obtained by condensing 4,4'-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA), and introducing ultra-low content of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) as a cross-linker. Cross-linked polyimide film (PCPI) is prepared by solution coating and gradient thermal imidization. The terminal amino groups of TAPP molecules form a covalent cross-linking network with PAA, and the porphyrin macrocycle π-conjugated system provides deep-level charge traps, significantly inhibiting high-temperature carrier migration. The breakdown strength of the optimal sample PCPI-0.1 reaches 475 MV / m at 200 °C, and the discharge energy density is 4.97 J / cm 3 , the charge-discharge efficiency is ≥85%. At the same time, it has a high glass transition temperature, high thermal stability, excellent cycle stability and film-forming uniformity. The solution coating process is simple to prepare, and the process conditions are simple and controllable, which is suitable for the batch production of high-temperature and high-energy storage polyimide dielectric films.