Abstract: Disclosed are a gallium 68 labeled affibody protein PET imaging agent and a use thereof; the imaging agent comprises 68Ga-Z-tri; the 68Ga-Z-tri is obtained by labeling an affibody protein with gallium 68; the affibody protein comprises a PDGFR-? targeting trimer affibody protein Z-tri; and the amino acid sequence listing of the affibody protein Z-tri is as shown in SEQ ID NO. 1. According to the present invention, the utilized PDGFR-? targeting trimer affibody having a unique amino acid sequence has the characteristics of high affinity and high stability compared with a monomer affibody and a dimer affibody, can greatly increase a nuclide labeling rate, and achieves the effectiveness thereof as a PET imaging probe.