A fused tricyclic compound and use thereof as a medicament, in particular as a medicament for the treatment and/or prevention of hepatitis B. Specifically, a compound having Formula (I) or a stereoisomer, a tautomer, an N-oxide, a solvate, a metabolite, a pharmaceutically acceptable salt or a prodrug thereof, wherein each variate is as defined in specification. The compound also includes a Formula (I) or a stereoisomer, a tautomer, an N-oxide, a solvate, a metabolite, a pharmaceutically acceptable salt or a prodrug thereof as a medicament, especially as a medicament for the treatment and/or prevention of hepatitis B.