Abstract: Water cooling unit for forced cooling during laser metal deposition process was developed and used in laser metal deposition of IC10 directionally solidified superalloy to enhance production efficiency and alloy quality. The microstructures and microhardness of laser deposits were compared for different cooling conditions. The results showed that the morphologies of deposits were changed that volume fractions of columnar grains increased and longer directional solidification columnar grains were obtained with forced cooling. In addition, the forced cooling had no obvious effect on the microhardness of each region in the deposits, but the high microhardness region was enlarged because of larger columnar grain zone when forced cooling was present.