The invention discloses a molybdenum-based thulium oxide material for a nuclear reactor ash control rod and an application of the molybdenum-based thulium oxide material. The molybdenum-based thulium oxide material is prepared by the steps of mixing after weighing dried thulium oxide powder with the purity of higher than 99% and dried molybdenum powder with the purity of higher than 99.5% according to the mass percentage of Mo-(3-55)wt% Tm2O3 under the protection of inert gases; then, adding a process control agent, and enabling the final mass concentration of the process control agent not to exceed 2.5wt% to obtain mixed powder; carrying out ball milling on the mixed powder for 2-160h in a way of stopping for 4-12min after ball milling for 45-60min under the conditions that the ball material ratio is (0.8-35):1, the filling coefficient is 0.05-0.85 and the ball milling rotating speed is 80-650rpm; next, carrying out isostatic cool pressing on the ball-milled mixed powder at the pressure of 80-550MPa for 0.05-4h to form a blank; and then, sintering the blank at 1200-1900 DEG C for 2-110h under the protection of the inert gases to obtain a molybdenum-based thulium oxide pellet which is an excellent neutron absorber pellet material for an ash control rod.