Objective To investigate the pathogenesis of neonatal necrotizing enterocolitis (NEC), to explore the laboratory basis for endogenous protective substance. Method Experimental models of both ischemia/reperfusion (I/R) group and ischemic preconditioning (IPC) group were set up using healthy male Wistar neonatal rats. Serum CGRP concentration, activity of LDH, the contents of MDA and the ratio of wet weight/dry weight (WW/DW) were measured respectively. Pathological sections of small intestines were prepared and observed under microscope. Results The serum CGRP concentration were statistically different between one group to another [control vs IPC: (124?10)pg/L vs (292?17)pg/L( q =42.01); control vs I/R: (124?10)pg/L vs (162?24)pg/L( q=7.16 ); control vs IPC+I/R:(124?10)pg/L vs (282?19)pg/L( q=35.76 ); IPC vs I/R: (292?17)pg/L vs (162?24)pg/L,( q=21.73 );I/R vs IPC+I/R:(162?24)pg/L vs (282?19)pg/L,( q=19.19 ; all P 0.05)]. CGRP concentration in IPC group was higher than that in control and I/R group. Serum LDH concentration was higher in I/R group than that in control group[(190?24)u/L vs (46?9)U/L( q=26.70,P