The invention relates to an obtaining method of a 
large deformation pipe line steel 
double phase structure. The obtaining method comprises the following steps: 1, carrying out compound design on a small part of 
pipe line steel according to design requirements; 2, determining a 
continuous cooling transformation curve (CCT curve) of the small part of the designed steel, wherein the CCT curve reflects a structure transformation law of the steel at different 
cooling rates; 3, selecting a 
cooling rate range meeting a requirement of 
bainite and ferrite 
double phase structure formation on the CCT curve; 4, determining various 
phase change points corresponding to the 
cooling rate range; and 5, determining the most important process parameters during steel manufacturing according to the determined 
phase change points, wherein the two most important process parameters comprise a 
cooling temperature and a 
cooling rate. According to the present invention, according to the existing process, the obtained 
cooling temperature and the obtained cooling rate are adopted to carry out 
batch production of 
steel plates, wherein a uniform elongation rate of the obtained 
double phase structure 
large deformation pipe line steel can be more than 12%, a working hardening index can be more than 0.15, and a 
yield ratio can be less than 0.77 so as to meet requirements on the 
large deformation pipe line steel in the standard.