Regeneration, replacement and washing of ion exchange resin are the important steps in the working course of condensate mixed bed, which effect directly the quality of out-flow and self-using water ratio. The acting characteristic and rule of macro-porous resin used in condensate fine treatment process have been studied. The rule of pH variety of drainage replacement is obtained. The apt pH values of cation and anion resin replacement end- point are put forward. At the same time the variational characteristic of drainage water quality is obtained when resin is washed. The conductance value, when cation and anion resin are washed solely is put forward. It is concluded that when cation and anion resin are too much, there is no need to prolong the washing time.