The invention relates to a method for absorptively separating low-concentration heavy-metal ions by utilizing graphene oxide colloid. The method is characterized in that the graphene oxide colloid is sealed inside a dialysis bag to be placed into the heavy-metal ion solution, the heavy-metal ions can be rapidly and high-efficiently adsorbed by a dialysis film, the heavy-metal ions can be separated and enriched, after the graphene oxide absorbing the ions is treated in an acid solution, the heavy-metal ions can be desorbed high efficiently, the graphene oxide is renewable and recyclable, since the graphene oxide in the dialysis bag cannot penetrate through the dialysis bag and does not enter the absorbed water solution, the secondary pollution of the adsorbing agent can be avoided, and the solid-liquid separation volume can be greatly reduced. The method is simple to implement, large in adsorption capacity and high in speed, the heavy-metal ion pollution of the water can be high-efficiently and rapidly treated, the ecological environment can be protected, and an important significance on promoting the economic sustainable development can be realized.