The behaviours of complexation and dissolution of PbCl_2 on the surface of galena were investigated to explore the process of hydro-chemical conversion of galena (PbS) in chloride media. By means of solution chemistry calculation, the production and dissolution of the products PbCl_2 were studied. And the passivation of the galena was studied by Tafel curve. The results show that PbCl_4~(2-) is the main form of PbCl_2 presented in the saturated potassium chloride (KCl) solution. The PbCl_2 crystal is easy to precipitate when the total concentration of chloride ion ([Cl-]T) is equal to 0.92 mol/L, and it is inclined to dissolve when [Cl-]T is more than 0.92 mol/L. The chloride complexing reaction rate strongly depends on the Fe~(3+) ion concentration when it is less than 6×10~(-4)mol/L, while passivation occurs on the surface of the electrode when Fe~(3+) concentration is larger than 6×10~(-4)mol/L. The reaction rate increases obviously when KCl is added, since the activity of Cl- increases; thus accelerates the dissolution of PbCl2.