The purpose of this study is to evaluate the effect of antimony addition on the weldability of sulfur dew-point corrosion resistant steel. The Gleeble hot ductility test ' Y-groove test ' maximum hardness test of heat-affected zone (HAZ), and actual welding test were carried out to evaluate the weldability of the steel. Three kinds of welding processes were used that is, shielded metal arc welding ' gas metal arc welding ' and submerged arc welding during actual welding. Furthermore ' the post weld heat treatment (PWHT) was carried out with 160℃×40hrs and 600℃ ×lhr for the submerged arc weldment. In addition, all weldments were subjected to the corrosion and charpy tests. The microstructure of HAZ and segregation area of base metal originated from casting process were examined, OM,SEM, and EPMA. The results showed that the addition of Sb below 0.1% had no significant effect on the hot ductility of HAZ of the steel without Mo However ' the addition of Sb greatly deteriorated the hot ductility of HAZ of the steel with Mo. The cold cracking defect in HAZ did not occur when the electrode with low hydrogen content was used. The charpy absorbed energy of as-welded HAZ was the same as that of base metal. In addition, the temper embrittlement in HAZ did not occur after PWHT, because the charpy absorbed energy of HAZ was higher than those of base metal and as-welded HAz. The local corrosion in HAZ of weldment would occur at the severe corrosion environment, and the higher the heat input, the wider the local corrosion area. Therefore, the low heat input welding process should be used during the joining of the steel to decrease the local corrosion in HAZ.