Through thermodynamic calculation and electrochemistry analysis, taking the galena as example, the basis for collector matching in origin potential flotation (OPF) was studied. The results of thermodynamic calculation show that the upper limit value of pH and flotation potential of diethyldithiocarbamate (DDTC) is higher than that of xanthogenate (KBX), which indicates that the collecting ability of DDTC for galena is better than KBX. The results of the interface capacitance analysis show that lead diethyldithiocarbamate (PbD2) is more steady than lead xanthogenate (Pb(BX)2) on the galena surface in the oxidation condition; the resistance analysis shows that D2 (DDTC oxidizes into its dimmer) and dixanthogen (BX) 2 would occur non-faradic desorption on the pyrite electrode surface when the potentials are respectively above 0.13V and 0.2V. Then synthetical criterion ΔE of collecting ability and selectivity was proposed. The results forecasted by this criterion were confirmed through flotation experiments of ore.