The optimization of electric resistance welding conditions has been investigated in order to improve the resistance to hydrogen induced cracking at bondline in API 5L X60 line pipes from center-slit coils. It was found that the elongated (Si, Mn, Al) rich oxide inclusions at bondline provided a preferential site for HIC, but no evidence on the center segregation effects was found. Design of experimental (DOE) method was used to find out the optimum ERW condition in the viewpoint of the minimization of defects ratio at bondline. The optimum ERW condition suggested by DOE successfully led to an excellent HIC resistance at bondline. Furthermore, it was observed that there was no relation between segregation and HIC resistance at bondline.