Abstract: In the thesis, the influence of microelements yttrium (Y) and tellurium (Te) on the diffusible hydrogen in weld bead has been firstly investigated in systemic way by means of alloying addition in the weld pool(AAWP).The results indicate that AAWP may no tably decrease the diffusible hydrogen,decrease the burn of precious microelements and improve the technological properties compared with the common alloying addition in the coating of coated eletrode. Thus the microelements will play an important role in further developing the welding materials and improving the quality of welding engineering.Finally the mechanism of microelements Y and Te reducing hydrogen is analysed.