Abstract: Objective: To analyze the effect of CT spectrum diagnosis in patients with lymph node metastasis of tumor and its influence on the prognosis quality of patients.Methods: in our hospital from April 2016 to November 2017 were pathologically diagnosed malignant tumor in 60 cases, according to the patient's disease occurrence site will be divided into lymphoma group, lung cancer group and cholangiocarcinoma group three, lymph node number of patients in three groups were 26, 30, 32. For patients in each group received CT spectral imaging value in different energy CT groups were compared for patients with lymph node and prognosis of patients according to the results, the range of spectrum should be kept between the 40~140 keV gradient was 10, comparison of different groups of patients between moisture and iodine content in the same energy in lymph nodes..Results: energy up to 70 kev as the most clear, this value applies in both groups of patients, the same energy state, each group of patients with metastatic lymph nodes of iodine content and CT value size relationship:Lymphoma Group > lung adenocarcinoma group > bile duct group (P<0.05); groups of patients with metastatic lymph nodes the water content of the difference was not statistically significant (P>0.05), the prognosis of patients with lymph cancer group was significantly longer than that of other groups in practice (P<0.05). Conclusion: the application of CT of lymph node metastasis in patients with disease diagnosis through detection of iodine content in judging patients with disease onset, obvious difference in 70 keV the CT node metastatic lymph nodes from different sources, which can be used to transfer energy standard in lymph nodes.