With the increase of wall thickness of pipeline steel,DWTT fracture toughness has become more and more sensitive to production process,including alloy design and processing,so it need more tight and more systematic control from the alloy design,reheating,rolling and finally cooling to improve upon DWTT property of heavy gauge X80 strip.In this paper,Through hot simulation and subsequent analysis,three points are significant to ensure DWTT property of 22mm X80 strip,including improvement Tnr by adding high Nb addition,increasing pass reduction in the rough rolling stage,and as well as low coiling temperature for obtaining dispersed,uniform MA constituents.As shown from test results,through reasonable alloy design and processing optimization,austenite grain size of 22mm X80 strip can be controlled to less than 9 m,volume fraction of MA constituents less than 10 percent with a size less than 2 m,which is significant to fulfill fracture toughness requirements of hot rolled X80 strip.Based on solid theoretical foundation and tight control,the test results of DWTT of 22mm X80 strip fulfill 85 percent in shear area at-15℃.