Abstract: Conducted are the oblique Y shape bevel welding crack test and the HAZ highest hardness test to the 1 100 MPa high strength steel for construction machinery purpose so as to study the welding process for it. It is demonstrates via the said tests that there exists a hardening tendency in the HAZ of the steel, therefor low hydrogen-contained welding material should be used, and post-welding dehydrogenation treatment has to be taken;when welding after pre-heating, the HAZ highest hardness decreases to a certain extent, so pre-heating should be done before welding so as to prevent occurrence of the welding cold cracking;since when the pre-heating temperature is more than 200 ℃, no weld crack develops, the welding process as requiring the pre-heating temperature higher the 200 ℃ should be used.