Disclosed in the present invention is a new11-oxo-7,11-dihydro-6h-benzo-[f]pyrido[1,2-d][1,4] azepine oxepin-10-carboxylic acid derivativeserving as a hepatitis B virus surface antigen inhibitor. Specificallydisclosed are a compoundrepresented by formula (V) or a pharmaceutically acceptable salt thereof, andapplications of thecompound represented by formula (V) or the pharmaceutically acceptable saltthereof and apharmaceutical composition thereof in the treatment of viral hepatitis B.(see formula V)