Therefore, this paper combined MTV, TLG and SUVmax to analyze the relationship between 18F-FDG metabolic parameters and CRC immune microenvironment (PD-L1 expression), and to evaluate the expression level of PD-L1 in patients undergoing surgical colorectal cancer resection with 18F-FDG PET/CT before surgery. The gene discussed is CD274; the disease is colorectal carcinoma.