Disclosed is a nitrile derivative compound represented by formula (I), a stereoisomer, a deuterated product, a co-crystal, a solvate or a pharmaceutically acceptable salt thereof, wherein each group is as defined in the description. The compound has dipeptidyl peptidase 1 inhibitory activity and can be used to prepare a drug for treating diseases including obstructive airway diseases, bronchiectasis, cystic fibrosis, asthma, emphysema, and chronic obstructive pulmonary diseases.