The corrosion inhibiting behavior and the change of concrete properties after the addition of a new rebar corrosion inhibitor DETA TU were studied by EIS method. The results show that the resistance of both concrete pore solution and the charge transfer of rebar corrosion process are increased. It has been proved that DETA TU is a dual function corrosion inhibitor, namely, it can cut out part of the capillary in the concrete as well as build up a protective layer on the rebar surface. The results after long period immersion show DETA TU has a good water resistance. Compared with nitrite, DETA TU has a different corrosion inhibiting mechanism.