Abstract: This is an essay in the field of mineral processing engineering. This work investigates the effects of two cationic collectors, dodecyl amine (DDA) and dodecyl trimethylammonium chloride (DTAC), on flotation of quartz. Based on micro flotation tests, adsorption measurement, zeta potential measurement and infrared spectrum analysis, the author studied the recovery of quartz, the adsorption of the two kinds of collectors on quartz and the changes of zeta potential of quartz influenced by the collectors at different pH condition and concentration. The results of the experiments show that the recovery of quartz can be increased to approximately 100% by both dodecyl amine and DTAC, with 1×10^-4 mol/L concentration, at neutral pH condition, however, at much lower pH condition, neither of the collectors can get a decent recovery of quartz. Additionally, in this concentration, the isoelectric point of quartz is able to be pushed to almost pH value 4 from around pH value 3 by both of the collectors; at neutral pH condition, with the concentration of either of the two collectors climbing, the zeta potential of quartz can be turned from negative to positive; at strong alkaline conditions, due to the disparities of the molecular structures, the types of the adsorptions are not exactly similar.