Serving as targeting ligands, aptamers have shown promise in precision medicine. However, the lack of knowledge of the biosafety and metabolism patterns in the human body largely impeded aptamers' clinical translation. To bridge this gap, here we report the first-in-human pharmacokinetics study of protein tyrosine kinase 7 targeted SGC8 aptamer via in vivo PET tracking of gallium-68 (Ga) radiolabeled aptamers. The specificity and binding affinity of a radiolabeled aptamer, named Ga[Ga]-NOTA-SGC8, were maintained as proven in vitro. Further preclinical biosafety and biodistribution evaluation confirmed that aptamers have no biotoxicity, potential mutation risks, or genotoxicity at high dosage (40 mg/kg). Based on this result, a first-in-human clinical trial was approved and carried out to evaluate the circulation and metabolism profiles, as well as biosafety, of the radiolabeled SGC8 aptamer in the human body. Taking advantage of the cutting-edge total-body PET, the aptamers' distribution pattern in the human body was acquired in a dynamic fashion. This study revealed that radiolabeled aptamers are harmless to normal organs and most of them are accumulated in the kidney and cleared from the bladder via urine, which agrees with preclinical studies. Meanwhile, a physiologically based pharmacokinetic model of aptamer was developed, which could potentially predict therapeutic responses and plan personalized treatment strategies. This research studied the biosafety and dynamic pharmacokinetics of aptamers in the human body for the first time, as well as demonstrated the capability of novel molecular imaging fashion in drug development.