The comparison of flow field and heat transfer characteristics for the new mist/steam working fluid inside the U-shaped internal cooling channel of the gas turbine blades roughed with new V-45 deg. Column-Row-Ribs and V-45 deg. solid ribs are conducted under the limited working conditions in this work. First, the secondary flow vortex and droplets distribution in channels with different turbulators were analyzed. Then, qualitative heat transfer comparison of these two different ribbed channels was conducted. Furthermore, the quantitative analysis of heat transfer enhancement and heat transfer uniformity was presented under the condition of different mist/steam mass ratio (mist/steam) and droplets diameter (D-0). Through the analysis, it is seen that the Mainstream Secondary Flow Vortexes in U-shaped channel roughed with 45 degrees V-shaped Column-Row-Ribs has the similar structure as the channel with 45 degrees V-shaped solid ribs. The droplets have a more even distribution in U-shaped channel roughed with 45 degrees V-shaped Column-Row-Ribs than channel with 45 degrees V-shaped solid ribs. And the new Column-Row-Ribs will help to solve the problem that the droplets deposit at the windward side of the solid ribbed channel, which benefits to promote the heat transfer evenness of the heated wall. The results proved that the U-shaped channel with 45 degrees V-shaped Column-Row-Ribs cooled with the mist-steam coolant has better heat transfer characteristics than the 45 degrees V-shaped solid ribs. For the U-shaped channel, there exists a best droplet diameter which can achieve the highest heat transfer enhancement.