Cationic dyes and metal ions in wastewater are considered as environmental pollutants. In order to treat these pollutants individually polystyrene (PS) and poly (styrene-co-butyl acrylate) (P(St-co-BA)) were first electrospun into fibrous membranes with a porous structure and then two simple modification methods were adopted to introduce -SO3H and -COO- groups into the PS fibrous membranes' and the P(St-co-BA) fibrous membranes' surfaces, respectively; finally the modified samples were used individually to adsorb either cationic blue dyes or copper ions, respectively. The results showed that the PS fibrous membranes were hydrophobic before modification but they became hydrophilic after modification due to the introduction of -SO3H. Then the modified PS fibrous membranes had the capability to adsorb cationic blue dyes from water, and their adsorption efficiency, with an adsorption time of 300min, reached 68.1%. For the P(St-co-BA) fibrous membranes, the -COO- groups were introduced into their surfaces after hydrolysis in alkali lye; however, they showed very weak adsorption capability for copper ions due to the loss of the fiber-web structure. In addition, the thermal properties of the fibrous membranes before and after modification were analyzed, and the morphology was also observed by field emission scanning electron microscopy.