In this paper, carboxymethyl-hydroxypropyl-β-cyclodextrin polymer modified magnetic particles Fe3O4 (CM-HP-β-CDCP-MNPs) were prepared and applied to magnetic solid phase extraction of malachite green combined with UV-Visible spectrometry detection. The synthesized magnetic particles were characterized by element analysis, Fourier transform infrared spectra and transmission electron microscopy. Several variables affecting the extraction and desorption of malachite green such as pH, the amount of adsorbent, the type and volume of eluent, extraction and desorption time, and temperature were investigated. Under the optimum conditions, malachite green could be adsorbed by CM-HP-β-CDCP-MNPs(RE%=92), and elution by C2H5OH(EE%=90). the preconcentration factor of the proposed method was approximately 7.5, the CM-HP-β-CDCP-MNPs could be used repeatedly for 5 times and offered better recovery. The linear range and detection limit (DL) were found to be 0.08～8.00 μg·mL-1 and 5.6 ng·mL-1 respectively. This technique had been successfully applied to the determination of malachite green in real samples.　The inclusion interaction of CM-HP-β-CDCP-MNPs with malachite green was studied through FTIR.