This study is a diagnostic study. Subjects were enrolled from clinical stage IIIB or IV NSCLC patients who received standard first-line chemotherapy combined with PD-1 monoclonal antibody immunotherapy and received 18F-FDG PET/CT imaging before treatment, after 2 courses of treatment, and at the time of disease progression.At the same time, the blood routine, liver and kidney function, inflammatory indexes and other laboratory data of the subjects participating in the study were collected. Based on 18F-FDG PET Ipercist standard and comprehensive laboratory indicators, the subjects were evaluated for tumor biological characteristics prediction and clinical staging, PD-1 immune efficacy monitoring and evaluation, tumor recurrence monitoring and re-staging. At the same time, the systemic immune response and immune-related adverse events during the treatment process were evaluated in order to establish a better evaluation standard and system for the comprehensive evaluation of PD-1 immunotherapy.This study plans to set the sample size as 50 cases.