Disclosed are a film containing an alginate membrane layer and a method for preparing the same. The method is as follows: using a thin layer carrier capable of absorbing liquid, the carrier being made of non-woven fabrics, textures, porous spongy films or plastic films, etc. formed from at least one synthetic or natural fiber； then using at least two coating procedures, which are separate but continuous in succession, to uniformly coat at least one surface of the thin layer carrier with a layer of aqueous alginate solution containing a proper weight percent of sodium alginate or potassium alginate and a layer of salt compound aqueous solution containing a proper weight percent of divalent metal ions such as calcium ions, respectively； rendering the divalent metal ions in the alginates and salt compound cross-linked, so as to form a colloid complex membrane layer, which has a net structure and is water insoluble, on the surface of the thin layer carrier, including on the surface or penetrating more deeply into the inner layer of the surface； thereby producing a film with a membrane layer of alginates such as sodium alginate and with a film carrier in a continuous, fast way in a large amount. When the thin layer carrier has a coarse surface, the formed alginate membrane layer is combined with the thin layer carrier together； and when the thin layer carrier has a smooth surface, the formed alginate membrane layer is easy to separate from the thin layer carrier, so as to enlarge the application range of the film.
