Abstract: 690 nickel based materials for the welding of nuclear device have serious hot crack sensitivity. As an industry recognized international difficult problem,their test and evaluation method are very important. By STF test,varestraint test,remelting experiment,longitudinal section test and large thickness crack test,the hot cracking sensitivity of 690 nickel-based wire was tested,analyzed and evaluated. Results show that the crack sensitivity of FM52M wire is the lowest,cracks appear when WHS690M wire was used in welding large thickness plate and all the performances of WHS694M wire are excellent,its crack sensitivity is equivalent to that of FM52M.