The viruses have been closely connected with human history, expanded their territories. There are many types of viruses around us such as high mortality virus, pandemic virus, and chimeric mutant virus, etc. To protect human beings from these harmful viruses, rapid diagnosis-system and effective reagent to inhibit the viral replication are necessary.In the part I, I focused on the influenza A virus for the sensing target virus and performed Counter-SELEX up to 14 round to isolate H1 specific aptamer between H1N1 and H5N2. The 14th round ssDNA pool showed a high affinity and selectivity to purified GST-HA1(H1N1). The 14th round ssDNA pool was cloned and obtained 22 ssDNA sequences and found four ssDNA aptamer candidates, which had high affinity to H1-HA1 and low affinity to H5-HA1 using reverse and sandwich ELISA. Finally, a class of novel, specific and distinguishable ssDNA aptamers against H1-HA1 was identified that was confirmed with ELISA, SPR, and western blot analysis. I hope these aptamers would have wide applications in diagnosis, therapy and prevention of influenza virus.In the part II, the screening assay was performed for finding effective inhibitors against viral replication. SARS-CoV Helicase/NTPase is the target protein of part II. The Helicase/NTPase is regarded as a good target for the development of antiviral reagent because of its essential role in replication cycle. The screening system was designed and found out several chemical compounds that inhibit ATP hydrolysis activity, dsDNA unwinding activity or both activities of SARS-CoV NTPase/Helicase using a FRET based dsDNA unwinding assay and a malachite green based colorimetric ATPase assay. A group of compounds known as kinase inhibitor was used for the screening. And several chemical compounds were selected and indicated the IC50 value in a micro molar range. This screening system can be introduced for many different types of viruses to select inhibitors.