The invention discloses a low-voltage flexible electrothermal film and a preparation method therefor. The electrothermal film comprises an insulating base material, an electrode layer, a conductive heating layer, a heat conducting and infrared radiation layer and an externally connected wire; each layer is formed by printing, and drying is completed in a drying channel; and the electrothermal filmis applicable to electrothermal clothes. The low-voltage flexible electrothermal film has the advantages as follows: large-area heating at a low voltage (3.7V) can be realized; the heat conducting and radiation layer is adopted to replace an insulation protection layer above the existing heating layer; the layer also has the insulation protection, heat conducting and infrared radiation functions;by adopting the multi-point externally connected wire mode to replace the existing method for improving conductivity of an external electrode, basically same voltages in each point on the external electrode is realized, so that cost is lowered, and meanwhile, electrode flexibility and stability are reinforced; and a mature printing mode is adopted to manufacture the electrothermal film to replacethe existing troublesome, time-consuming and strict working procedure, so that the technical threshold for manufacturing the low-voltage flexible electrothermal film is lowered, thereby facilitatinglarge-scale industrial production of the electrothermal film.