Abstract Additive manufacturing enables quick development and implementation of innovative designs, especially for gas turbine cooling. This layer-by-layer manufacturing technique affects the dimensional accuracy and the surface roughness of the components. In this study, both conjugate heat transfer simulation and cooling effectiveness test are carried out to study the effect of 3D printing on the heat transfer performance. To achieve the profile of a 3D-printed vane, a reverse modeling process was proposed with the coordinate measurement data. Compared to the designed vane, the maximum profile deviation at the leading-edge area can be up to 0.53 mm. Simulation results show that the profile deviation can change the location of the aerodynamic stagnation point, which causes the temperature to increase more than 40 K at the leading edge. This phenomenon is also validated with the cooling effectiveness test of the vane. Test results show that the temperature distribution agrees well with the conjugate heat transfer analysis employing the model of the 3D-printed vane. The maximum relative deviation of temperature on the pressure side and most of the suction side is less than 5%. At the trailing edge on the suction side, the relative difference of temperature can be up to 10% which is caused by the mini-channel surface roughness. Hence, when additive manufacturing is applied in the blade cooling structure validation, both profile deviation and surface roughness should be considered carefully.