The invention belongs to the technical field of polypeptide preparation, and in particular, relates to a 
fusion protein and a method for preparing a 
liraglutide intermediate polypeptide GLP-1 (7-37).The method includes the main steps: constructing recombinant 
liraglutide intermediate 
engineering bacteria, expressing a GLP-1 (7-37) 
fusion protein by culture and induction of 
escherichia coli, and carrying out denaturation, renaturation, 
enzyme digestion and separated purification to obtain the intermediate polypeptide GLP-1 (7-37). Through changing a sequence of leading 
peptide, the expressionmode becomes an 
intracellular insoluble inclusion body expression, and the expression quantity is remarkably increased; 
inclusion bodies after washing are dissolved at high pH, and a large amount of denaturants are not needed to use, the 
inclusion bodies after washing are added to a inclusion body dissolved 
buffer solution at a 
high protein concentration of 5-40 g / L, the renaturation time does notexceed 1 h, and enterokinase 
digestion is carried out immediately after 
dissolution; the renaturation process can be reduced, the 
enzymatic digestion system is reduced, the cost of chemical reagentscan be reduced, and industrial amplification is facilitated; 
ion exchange separation and purification can be used, and the separation degree is high. The prepared 
liraglutide intermediate polypeptideGLP-1 (7-37) reaches 92% or more and the yield is more than 87%.