The effects of the nonmetallic inclusion and toughness on cold crack susceptibility were studied using high-strength armor grade casting steel. The cold cracking susceptibility of armor grade casting steel was evaluated using the newly proposed multi-layer weld cracking test and two different tempering conditions were granted for casting steel toughness. The results showed that nonmetallic inclusion is acted as the cold crack initiation place and cold crack was developed and propagated along with nonmetallic inclusions and connected with other cold cracks. Also, voids, which were created that nonmetallic inclusions were moved to the weld metal and vicinities because of welding heat input were acted as the initiation point for cold crack on casting steel weldment. Toughness gave effects on cold crack initiation and propagation. Even tough, some voids and nonmetallic inclusions were placed on the HAZ and some micro cracks were observed around voids. Higher level of toughness weldment did have resistance to the cold crack.