In this research, the magnetite polystyrene maleic anhydride (MPSMA) was synthesized and structure and morphology characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy techniques. The obtained nano-structured inorganic material was employed as a novel magnetic nanosorbent for separation and pre-concentration of Methyl violet (10B) dye from aqueous solutions, which can be spectrophotometrically monitored at λ = 585 nm after pre-concentration by solid phase extraction (SPE). The effect of several parameters including pH of the sample solution, amount of the sorbent, extraction and desorption times, and elution conditions and sample volume were investigated and optimized. UV–Vis spectrophotometer was used for determination of MV (10B) concentration after desorption of the dye by nitric acid solution. Under the optimum experimental conditions, the limit of detection and the relative standard deviation were 0.08 µg L–1 and 1.10 %, respectively. The enrichment factor of 200 was achieved and the calibration graph using the presented solid phase extraction system was linear in the range of 0.3 – 1500 µg L–1 with a correlation coefficient of 0.9989. The method was successfully applied to pre-concentration of MV (10B) from several textile waste water effluents.