Malignant tumours always threaten human health. For tumour diagnosis, positron emission tomography (PET) is the most sensitive and advanced imaging technique by radiotracers, such as radioactive ¹⁸F, ¹¹C, ⁶⁴Cu, ⁶⁸Ga, and ⁸⁹Zr. Among the radiotracers, the radioactive ¹⁸F-labelled chemical agent as PET probes plays a predominant role in monitoring, detecting, treating, and predicting tumours due to its perfect half-life. In this paper, the ¹⁸F-labelled chemical materials as PET probes are systematically summarized. First, we introduce various radionuclides of PET and elaborate on the mechanism of PET imaging. It highlights the ¹⁸F-labelled chemical agents used as PET probes, including [¹⁸F]-2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]-FDG), ¹⁸F-labelled amino acids, ¹⁸F-labelled nucleic acids, ¹⁸F-labelled receptors, 18F-labelled reporter genes, and ¹⁸F-labelled hypoxia agents. In addition, some PET probes with metal as a supplementary element are introduced briefly. Meanwhile, the ¹⁸F-labelled nanoparticles for the PET probe and the multi-modality imaging probe are summarized in detail. The approach and strategies for the fabrication of ¹⁸F-labelled PET probes are also described briefly. The future development of the PET probe is also prospected. The development and application of ¹⁸F-labelled PET probes will expand our knowledge and shed light on the diagnosis and theranostics of tumours.