The invention belongs to the related technical field of a perovskite solar battery, and discloses a preparation method of a flexible trans-structured perovskite solar battery. The preparation method comprises the following steps of (1) performing evaporating on copper phthalocyanine on a cleaned flexible conductive substrate through a thermal evaporation method to form a hole transport layer; (2)spin coating the surface of the hole transport layer with a spin coating solution by adopting an anti-solvent method, and performing heating on the flexible conductive substrate to obtain a perovskiteoptical absorption layer; and (3) spin coating the perovskite optical absorption layer with a fullerene derivative solution to form an electron transfer layer; and then forming a counter electrode onthe electron transfer layer by adopting an evaporating method to obtain the flexible trans-structured perovskite solar battery. The invention also relates to the flexible trans-structured perovskitesolar battery. The preparation temperature and preparation cost are lowered, the battery performance is improved and relatively high flexibility is achieved.