At first there were made characteristic of some models of hydrogen induced cold cracking. After characteristic the real conditions of the cold cracking in weld joints shows the possibilities of used the threshold stress intensity factor KIthto evaluate the cold cracking resistance There also was established a modified van Leeuwen - Lancaster equation and determined the relation KIth/KIC. In this relation KIth/KICwas considered the influence of the constraint effect in mismatched weld joints on cold cracking resistance. It was received by introduce to calculation the constraint factor KWfor under - and overmatched weld joints. Finally, we were obtained the relation KIth/KICas a function of κ, q, C. Lastly was made some analytical examples.