The invention discloses a preparation method of a high-temperature resistant lithium battery. The preparation method comprises the following steps: (1), mixing polyimide with polycarbosilane powder toobtain a mixture, and dissolving the mixture in an organic solvent; (2), adding lithium ion salt into the solution obtained in the step (2), coating the solution on a cathode, volatilizing off the solvent under a high-temperature vacuum condition to form a polymer electrolyte membrane; and (3), preparing an anode on the polymer electrolyte membrane, and performing encapsulation to prepare the lithium battery. The preparation method of the high-temperature resistant lithium battery disclosed by the invention has the advantages that based on keeping the advantage of the gel-state polymer electrolyte, the related disadvantages are effectively overcome, the ionic conductivity of polymer is effectively increased, the mechanical strength of the electrolyte membrane and the ironic conductivity performance of the membrane are improved, and the situation that the battery has high conductivity in a temperature range of minus 20 DEG C to 80 DEG C is ensured, and requirements of the lithium battery in the fields of cleaning power, miniature and flexibility can be met; and moreover, a complicated abnormal structure can be prepared, so that the lithium battery has a wider application range, anda good technological progress is achieved.