Abstract: The copper-manganese mixed oxides prepared by coprecipitation were tested for water gas shift reaction on a micro-reaction system with on-line GC analysis and characterized by XRD，TEM，BET and TPR. The adding rate of precipitator has significant effect on the texture and activity. The copper-manganese mixed oxide with adding time of precipitator less than 33min presents higher activity, especially the higher thermo stability. The coppermanganese mixed oxide prepared at adding time of precipitator less than 160min are mainly consisted of Cu1.5Mn1.5O4. With the increasing of adding time of precipitator, especially for longer than 160min Mn2O3 appears. After catalytic reaction MnO, Cu and Cu2O are the crystalline structure of the samples. With the increase of Mn2O3 the activity, especially the thermo stability activities decrease. Therefore, it can be concluded that the adding rate of precipitator is most curial factor for the preparation of high performance coppermanganese mixed oxides for the water gas shift reaction.