Removal of fluorine in sodium aluminate solution facilitates the purity of aluminum products and reduces the corrosiveness of equipment. Hence, a modified synthetic method was used to prepare mayenite (Ca12Al14O33) adsorbent with the enhanced fluorine adsorption capacity in sodium aluminate solution. The adsorption process conformed to a pseudo-second-order kinetic model (R2 = 0.99) and Langmuir adsorption isotherm (R2 = 0.98) indicating that the adsorption of fluorine by Ca12Al14O33 is chemisorption. According to X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT − IR), X-ray fluorescence (XRF), and X-ray photoelectron (XPS) analysis, the mechanism of fluorine adsorption by Ca12Al14O33 was the ligand exchange with − OH and the formation of F − Al bond. Therefore, Ca12Al14O33 could be used as a potential adsorbent for fluorine in sodium aluminate solution.