Dipeptidyl Peptidase IV (DPP4), also known as CD26, is a kind of serine protease, can decompose the second N-terminal proline or alanine residue of the peptide chain. In organisms, dipeptidyl peptidase can rapidly decompose incretin, which can stabilize insulin level and promote the reduction of blood glucose level in organisms. The detection principle of this kit is that DPP4 can decompose the substrate and release the fluorescent substance AMC, and the activity of this enzyme can be inhibited by adding DPP4 inhibitor. The activity of DPP4 could be calculated by the difference of fluorescence value before and after inhibition.