Provided is the composition of a peptide and its mutagenic version, or other derivatives with the same 3-D structure with activity to bind the extracellular domain of PDGFR-α, or -β, but does not dimerize by itself, wherein said peptide comprises the sequence shown as SEQ ID NO: 1, 2 or 3. Also provided is the composition of the nucleotide sequence encoding said peptide and its derivatives, and the usage of said peptide and derivatives of the peptide in preparation of medicine for the prevention and treatment of fibrosis diseases, such as liver, kidney, and lung fibrosis, primary cancer, and cancer metastasis, especially stomach cancer, liver cancer, breast cancer, and lung cancer.