This study was performed to screen the sequence of specific nanobody targeting SARS-CoV-2 S protein,and to express and purify recombinant anti-SARS-CoV-2 nanobodies,and evaluate their characteristics and application potential.Based on the previously constructed natural bacteriophage nanobody display library,the anti-SARS-CoV-2 S protein nanobody sequences were screened,with biotinylated SARS-CoV-2 S protein receptor-binding domain antigen as target,by biotin-streptavidin liquid phase screening method,phage-ELISA and sequencing.Recombinant anti-SARS-CoV-2 S protein nanobody expression vectors were constructed,the protein was induced by IPTG and then purified,and their characteristics and application potential were analyzed by SDS-PAGE,Westem blot and ELISA methods.Two anti-SARS-CoV-2 S protein nanobody sequences were successfully obtained,and the corresponding prokaryotic expression bacteria were constructed.The recombinant anti-SARS-CoV-2 S protein nanobody was expressed and purified successfully,which can specifically bind to SARS-CoV-2 S protein.In conclusion,the recombinant anti-SARS-CoV-2 S protein nanobodies have screened and expressed successfully,which provides a basis for its application in SARS-CoV-2 detection and treatment,and facilitates related researches.