Abstract: Immunotherapy strategies of targeting PD-1 and its ligand PD-L1 are widely administered in varied types of cancer. Patient benefitting from PD-L1 targeted immunotherapy mainly depends on the expression level of PD-L1 in tumor tissues. Currently, the expression level of PD-L1 is primarily detected through the invasive method of biopsy in clinic, which is severely limited by the temporal and spatial heterogeneity of PD-L1 expression. Nuclear medicine probe can realize the noninvasive as well as in vivo detection of PD-L1 at the molecular level, which has important clinical significance for the guidance of patient screening and the prediction of patient's response to immunotherapy. This article reviews PD-L1 targeting nuclear imaging probes and their applications in tumor PD-L1 imaging.