Abstract: In this paper, quaternary ammonium salt dodecyl trimethyl ammonium bromide (DTAB) was used as collector, and the flotation behavior and mechanism of potassium feldspar and apatite in DTAB system were comparatively investigated. The flotation test results of pure minerals show that DTAB has excellent collecting performance for potassium feldspar in the range of pulp pH value from 6 to 11, while apatite has poor floatability. When the dosage of DTAB is 3×10^-5 mol/L and the pH is 9.45, the flotation recoveries of potassium feldspar and apatite are 93% and 2% respectively. From the artificial mixed ore with potassium feldspar and apatite in the mass ratio of 3 : 1, the apatite concentrate with P₂O₅ content of 34.85%, Al₂O₃ content of 1.52%, P₂O₅ recovery of 91.46% can be obtained, indicating that DTAB can realize the selective separation of potassium feldspar and apatite. The flotation test results of artificial mixed ore show that DTAB can realize the selective separation of potassium feldspar and apatite. The results of Zeta potential, XPS and FTIR results show that DTAB is selectively adsorbed on the surface of potassium feldspar through physical adsorption, but less on the surface of apatite. Microcalorimetric results show that the reaction between DTAB and potassium feldspar is more intense than that of apatite. The molecular simulation results show that the adsorption effect of dodecyl trimethyl ammonium bromide on potassium feldspar surface is obviously stronger than that on apatite.