The invention belongs to the field of medicine and discloses 6-oxo-1,6-dihydropyridine-3-formamide derivatives as well as pharmaceutical composition, a preparation method and an application thereof. The derivatives are selected from a compound represented as formula A in the description as well as stereoisomers, racemates, tautomers, isotopic labels, nitric oxide, hydrates, solvates or pharmacologically acceptable salts of the compound. Besides, the invention discloses the preparation method of the derivatives, the pharmaceutical composition containing the derivatives and the application of the derivatives to preparation of drugs for treating or preventing hepatitis b.