Abstract: To investigate the effect of twin screw extrusion on the digestion properties of jackfruit seed starch(JFSS)and glycemic index,the changes of the digestibility and digestibility dynamics of JFSS before and after extrusion were investigated by in vitro digestion test. On basis of this,the postprandial blood glucose level(PPBS)of JFSS before and after extrusion was predicted by enzymatic hydrolysis index(HI)and glycemic index(GI). The results indicated that the twin screw extrusion treatment increased the content of rapidly digestible starch(RDS)and slowly digestible starch(SDS),and enhance the equilibrium concentration(C_∞),enzymatic hydrolysis rate(k),hydrolysis index(HI),glycemic index(GI),and digestion rate of JFSS but significantly decreased the content of resistant starch(RS)(P<0.05). Under the low moisture content,with the increase of screw speed and barrel temperature,the content of RDS increased from 47.85% to 58.91%,and the values of k,C_∞,HI and GI also increased. The structure of JFSS changed from the compact structure to loose,porous polyhedral structure by twin screw extrusion.