Abstract: The present disclosure discloses a nano antibody for neutralizing a toxicity of SARS-CoV-2 and preparation method thereof. The nano antibody comprises a complementarity determining region CDR comprising a CDR1, a CDR2 and a CDR3; an amino acid sequence of the CDR1 is selected from at least one of amino acid sequences shown in SEQ ID NO. 1 and SEQ ID NO. 2; an amino acid sequence of the CDR2 is selected from at least one of amino acid sequences shown in SEQ ID NO. 3, SEQ ID NO. 4, and SEQ ID NO. 5; and an amino acid sequence of the CDR3 is selected from at least one of amino acid sequences shown in any one of SEQ ID NO. 6 to SEQ ID NO. 9. The nano antibody for neutralizing the toxicity of SARS-CoV-2 has the advantages of a small molecular weight, a high affinity with the SARS-CoV-2, a low production cost, and the like.