Preparation method for fused protein of human C-type diuresis promotion sodium peptide and human serum albumins and its product

The invention discloses a preparing method of fusion protein of human C-type natriuretic peptide (CNP) and human serum albumin (HSA) and product, belonging to the technical field of long-acting recombinant fusion protein drug, which comprises the following steps: adopting overlapping PCR technique; splitting HSA cDNA and CNP cDNA; integrating HSA-CNP cDNA fusion gene obtained without any connecting peptide being added into chromosome of a host; and expressing in the host system. The fusion protein of the invention includes a first area with at least 85% sequence homologous with human serum albumin and the second area with at least 85% sequence homologous with human C-type natriuretic peptide, individual amino acid residue substitution, deletion and addition can be carried out with the characteristics of the fusion protein being not changed.The fusion protein of the invention has extended half-life in the human body, with the physiological property of the human C-type natriuretic peptide being kept, improved s