A systematic investigation of the fabrication process, microstructure and treatment technology of the Rare earth oxide doped Mo cermet (REO-Mo in brief) on the secondary electron emission (SEE) mainly has been performed. The REO-Mo samples were fabricated by liquid-liquid, Liquid-Solid and Liquid-Liquid doping method and subsequently by the Spark Plasma Sintering (SPS) techniques. It was found that the uniform mixing of REO with Mo would have considerable benefit for enhancement of SEE coefficient (δ). Annealing the cathode in hydrogen (called as the pre-activation treatment) could greatly improve the SEE performance by removing the absorbed water and oxygen at the cathode surface which might cause the oxidation of molybdenum during cathode high temperature operation. It is found that the activation temperature of REO-Mo cathode annealed in hydrogen could decrease to 1000oC, about 300oC lower than that of the cathode without pre-activation treatment, which is favorable for the practical application.