The invention relates to a heavy metal ion adsorption film and a preparation method thereof. The heavy metal ion adsorption film is composed of polyvinyl alcohol and amido polymers at a polyvinyl alcohol/amido polymer ratio of (95:5) to (20:80). The amido polymers are polyvinyl amine, polyallylamine and branched polyethylene. The amido polymers are introduced into the aqueous solution of polyvinylalcohol and then the resulting mixture undergoes crosslinking reaction with a cross-linking agent to form a three-dimensional polymer network. The method is simple, feasible and free of organic solvents. The introduction of amido groups can efficiently increase the water swellability of polyvinyl alcohol film and simultaneously enhance the adsorbability of the film to heavy metal ions.