Recombinant Anti-albumin x Anti-IL-6R Bispecific Antibody (VHH-IgG) is formed by an IgG and two VHH fragments. The VHHs from an anti-IL-6R antibody variable domain are respectively connected to the N terminus of the anti-albumin IgG heavy chains or light chains to form VHH-(H)IgG or VHH-(L)IgG. It is a type of appended IgGs and has 2+2 antigen-binding valency. This BsAb can act as PK-modulated receptor antagonist. It is designed for the research of Systemic lupus erythematosus (SLE); Rheumatoid arthritis (RA).