Objective: To explore the absorption characteristics of marine fish oligopeptide chelated iron (MCOP-Fe) in small intestine， and compare it with the traditional iron supplement-ferrous sulfate (FeSO4). Methods: 40 female Sprague Dawley rats were randomly divided into 8 groups (L-MCOP-Fe: 3 μg/mL MCOP-Fe； M-MCOP-Fe: 5 μg/mL MCOP-Fe； H-MCOP-Fe: 10 μg/mL MCOP-Fe； L-FeSO4: 3 μg/mL FeSO4； M- FeSO4: 5 μg/mL FeSO4； H-FeSO4: 10 μg/mL FeSO4； H-MCOP-Fe+PA: 10 μg/mL MCOP-Fe+500 μg/mL phytic acid； H-FeSO4+PA: 10 μg/mL FeSO4 + 500 μg/mL phytic acid). To establish the model of everted gut sac in vitro， the effect of iron absorption in different intestinal segments was evaluated by the cumulative iron absorption rate per unit area(Q). Results: 1) The Q values of duodenum， jejunum and ileum in three MCOP-Fe groups increased with concentration gradient， but there was no similar trend in FeSO4 groups； 2) The Q values of group L-FeSO4 and M-FeSO4 had a tendency to be higher than those of group L-MCOP-Fe and M-MCOP-Fe， but were opposite at high concentration (10 μg/mL)； 3) After adding 500 μg/mL phytic acid， the Q values of groups H-MCOP-Fe+PA and H-FeSO4+PA decreased compared with groups H-MCOP-Fe and H-FeSO4， and the decrease degree of group H-FeSO4+PA was more significant (P<0.05). Conclusion: In the range of 3-10 μg/mL， the absorption rate of FeSO4 in small intestine showed an equilibrium trend of saturation， while the MCOP-Fe showed a gradient trend of increase； at the same time， MCOP-Fe was less inhibited by phytic acid， and was more stable than FeSO4， which has good application prospects.