Pure Mo and Mo-La2O3 bars with high transverse ductility were prepared by forging and upsetting. The microstructure and transverse bending properties of both bars were investigated after different annealing treatments. The results show that the pure Mo bars forged and upset by 85% possess good transverse ductility and the elongation reaches 5%, while that of the forged and upset Mo-La2O3 bars is only 2%. It is because the mobility of dislocations in the Mo bars is better than that of Mo-La2O3 bars in this condition. As the annealing temperature increases, the transverse ductility of the two kinds of bars is improved gradually; particularly the elongation of Mo-La2O3 bars annealed at 1200 oC for 1 h exceeds 10%, higher than that of pure Mo bars. In the upsetting process, many dislocation cells can be observed in the Mo-La2O3 bars, which disappeared little by little as the annealing temperature increased, and still there were a lot of tangled dislocations in the cells which were pinned by the dispersed La2O3 particles. The improvement of the transverse ductility of Mo-La2O3 bars is relative with the interaction between the La2O3 particles and dislocations. Both the Mo bars and Mo-La2O3 bars have recovery recrystallization process, and similar dislocation structure change