The mechanical properties of molybdenum wires doped with different contents of La2O3 were investigated systematically and the interaction between La2O3 particles with dislocations in MoLa2O3 wires were observed by SEM and TEM. It is shown that Mo-La2O3 wires possess much higher tensile strength than the pure Mo. In wires the dislocation motion is strongly hindered by La2O3 particles, which remains up to much higher temperature. Moreover, a number of prismatic dislocation loops and hexagonal dislocation network have been formed in annealed Mo-La2O3wires. The higher strength of Mo-La2O3 than the pure Mo is attributed to the La2O3 particles dispersion strengthening and dislocation strengthening.