Formylpyridine derivative having FGFR4 inhibitory activity, preparation method therefor and use thereof

Formylpyridine derivatives having FGFR4 inhibitory activities, a preparation method therefor and use thereof are described. In particular, the formylpyridine derivatives have a structure of formula (I), and the definition of each substituent in the formula are described in the description and claims. The series of compounds of the formula (I) have very strong inhibitory effects on FGFR4 kinases and very high selectivity, and can be widely used in the preparation of medicaments for treating cancers, particularly prostate cancer, liver cancer, pancreatic cancer, esophageal cancer, stomach cancer, lung cancer, breast cancer, ovarian cancer, colon cancer, skin cancer, neuroglioblastoma or rhabdomyosarcoma, and prospectively will be further developed to become a new generation of FGFR4 inhibitors.