Researched the corrosion behavior of TZM and La doped TZM alloy in acid and alkaline medium. Designed four corrosion period stages as 10days, 30days, 50days, 70days for respectively. Investigated and compared mass loss condition, weight loss condition, average corrosion rate and corrosion morphology. Anlysis the corrosion mechanism in acid and alkaline of TZM alloy and the effect of La doped on corrosion resistance of TZM alloy. The study shows TZM alloy corroded in acid major set off cell reaction and anode dissolved while cathode hydrogen evolution. Corrosion prior occurred at surface defect, impurty, grain boundary and dislocation. Crevice corrosion morphology was observed at the narrow slit which formed by scratch and width less than 0.0001 inch (0.025~0.1mm). Corrosion hardly occurred in alkaline medium. La doping could slightly rising the corrosion resistance of TZM alloy, but the improvement is not significant