In this study, zeolite synthesized based on bentonite via the alkali fusion-hydrothermal method, and the effects of different synthesis parameters on the crystallinity and silicon-aluminum ratio of zeolite were investigated. The zeolite particles were modified by cationic surfactant and magnetized to prepare a MCTAB-BZ composite, which was then applied to the adsorption of diethyl phthalate (DEP) from aqueous solution. The effects of operating factors, including pH value, adsorption dosage, temperature, and adsorption time on the kinetic and isotherm adsorption behavior were studied. Highly crystalline ANA-zeolite can be prepared with the alkali content of 1:1, the aging time of 20 h, the aging water content of 1:15, and the crystallization time of 24 h. The results of the adsorption experiment show that the novel adsorbent-MCTAB-BZ composite shows the best adsorption capacity when the adsorption dosage is 6.25 g/L, temperature is 30 °C and adsorption time is 180 min at the original pH value of the aqueous solution. The adsorption results are presented well by the pseudo-second-order kinetic model and the Freundlich isotherm model.