Abstract: The present application provides a VEGFR1 antigen polypeptide containing three polypeptides, namely H-DEGVYHCKATNQKGSVESSAYLTVQGTSDKSNLE-OH, H-DLKLSCTVNKFLYRDVTWILLRTVNNRTMHYSI-OH and H-ESGLSDVSRP SFCHSSCGHVSEG KRRFTYDHAEL-OH, and an application of the antigen polypeptide to detection of a serum immunity marker, namely a VEGFR1 autoantibody. The present invention also provides a method for detecting the serum immunity marker-VEGFR1 autoantibody by using the VEGFR1 antigen polypeptide described in the present application and a test kit containing the VEGFR1 antigen polypeptide.