Increasing the steel grade and gas pressure in pipeline project means the crack arrest toughness for pipe needs to enhance greatly. In this paper, effect factors of X80 toughness were studied. Through commercial production of X80 steel, it was found that the content of carbon or sulphur influenced impact energy obviously. Large numbers of statistical data showed that impact energy would well satisfy the requirement of X80 hot-rolled steel strip for the Second West -East Gas Pipeline if [C] was between 0.035 and 0.065 wt.% and [S] below 30 ppm. Through EBSD analysis, it was concluded that the effective grain size was smaller, toughness would be better. Fine and equably dispersed M-A structure would improve the strength, while structure with strip or sharp angel would deteriorate the toughness of X80 steel. Development of X80 strips for Chinese first full-scale burst test was also introduced in the paper.