The invention discloses a thin type battery and a preparation method therefor. The thin type battery comprises two parallel packaging layers, wherein horizontal outwardly-extended tabs are arranged on the packaging layers; a positive electrode active material layer and a negative electrode active material layer are arranged on the inner side of each packaging layer separately; an isolating membrane is arranged between the positive electrode active material layer and the negative electrode active material layer; each packaging layer comprises a protection layer and a metal layer that are superposed mutually; the positive electrode active material layer and the negative electrode active material layer are connected with the corresponding metal layer; and a sealing connecting layer is arranged on the edge between the two packaging layers. According to the thin type battery and the preparation method therefor provided by the invention, a thinner battery or a battery with higher energy density can be obtained; and namely, the battery can be thinner in thickness under the premise of maintaining the energy density of the battery, or the energy density of the battery can be improved under the premise of maintaining the thickness of the battery.