In this paper, the method of enzyme inhibition kinetics was used to study the inhibition, inhibition type and inhibition kinetic constants of morin on aminopeptidase N.The leukemia cell growth inhibition test was carried out,and the mechanism of interaction between Morin and aminopeptidase was studied by fluorescence spectroscopy.At last the impact of Morin on aminopeptidase N structure was further explored. The results showed that Morin was a reversible competitive inhibitor of aminopeptidase N (half-inhibition rate IC50 was 70.85 μM, inhibition constant Ki was 21.23 μM); deactivation kinetics time course analysis showed that Morin could quickly act with aminopeptidase N and rapidly reduce the activity of the enzyme; fluorescence spectroscopy showed that Morin could significantly quench fluorescence of aminopeptidase N, and hydrophobic interaction was the main driving force of the interaction between the two; circular dichroism analysis showed that Morin induced the unfolding ofaminopeptidase conformation , so as to increase the α-helical content,which was detriment to the formation of the active center, leading to the reduction of activity of tyrosine aminopeptidase N.