The present invention provides small molecule compounds of bisheterocycle in tandem having the structural formula of P1-P2, and the use thereof as well as a composition containing the compounds, each of P1 and P2 is an unsaturated 5-member heterocyclic ring having one or two heteroatoms. This compound may effectively inhibit the replication of influenza virus, the DNA replication of hepatitis B virus (HBV), and the formation of HBsAg and HBeAg. These compounds can be used for the preparation of a medicament for viral diseases, and may overcome the limitations of the known nucleosides drugs, including cytotoxicity, the requirement of other drugs having different structures for against the drug-resistant virus variants induced by long-term therapy. The structure of the compounds according to the invention is relatively simple and easy to be prepared.