Single-domain antibody for CD47

The invention discloses a single-domain antibody, and particularly relates to a single-domain antibody for a CD47 extra-cellular fragment. An amino acid sequence is indicated as SEQ ID NO.9. The single-domain antibody consists of 4 framework areas and 3 complementary decision areas, the amino acid sequence of the four framework areas is indicated as SEQ ID NO. 1, SEQ ID NO.2, SEQ ID NO.3 and SEQ ID NO.4, the amino acid sequence of the three complementary decision areas is respectively indicated as SEQ ID NO.5, SEQ ID NO.6 and SEQ ID NO.7. The invention discloses nucleic acid for encoding the single-domain antibody, an expression carrier comprising the nucleic acid and a host cell comprising the expression carrier. The single-domain antibody for the CD47 can be specifically combined with CD47 and is wide in application prospect for researching the CD47 curative antibody medicine.