weld metal’s Microstructure of HSLA steel is make up of proeutectoid ferrite, Ferrite Side Plates and acicular ferrite. Acicular ferrite possesses good toughness and strengthen. We wish to get acicular ferrite in weld metal of HSLA steel.This article expounds the acicular ferrite form from alloy elements,welding parameters and inclusions, aiming to provide some information on the welding of the steel and the research and development of welding materials.