In this study, a laser deep-penetration welding experiment was conducted on an X65 steel pipeline using a Nd∶YAG laser. The morphology of the created weld was observed using a optical microscope. The microstructure of the weld area was characterized by a scanning electron microscope and its hardness was measured by a hardness tester. Results show that the weld depth of the steel sample decreases from 8 mm to 4 mm because of the variation in welding deflection angle, which affects the energy distribution of the laser in space. It is also observed that the weld profile deflects along the laser deflection angle in the direction of welding thickness. At the end of the welding process, a crack associated with temperature and temperature gradient is observed on the weld due to reduction in welding speed. However, as the welding speed increases, the width of the weld heat-affected zone narrows, and the maximum hardness of the weld zone increases from 472.1 HV to 565.5 HV. The asymmetry in the hardness distribution of the fusion zone increases with the increasing welding speed.