For the problems of the ductility dip cracking（DDC） susceptibility of deposited metal of 690 nickel base alloy at high temperature,a strain-to-fracture（STF） test based on Gleeble-3500 thermo-mechanical simulator is performed to evaluate the DDC susceptibility of WHS690M and Inconel 52 M. The results show that the minimum critical strain of the DDC of deposited metal appears at the temperature about 1 050 ℃,and welding heat input has little effect on the minimum critical strain. Comparing with the deposited layer of large-area surfacing,the critical strain of butt weld deposited metal reduces,and DDC susceptibility increases.