To investigate the CT features and risk factors of lung metastasis in senile colorectal cancer in order to provide reference for clinical diagnosis and treatment.

420 elderly patients with colorectal cancer admitted from August 2016 to August 2019 were retrospectively analyzed and divided into lung metastasis group and control group according to whether lung metastasis occurred. All patients were diagnosed with chest and abdominal enhanced CT and their features were recorded. All patients were followed up for 3 years. SPSS 22.0 statistical software was used to analyze the risk factors of lung metastasis in elderly colorectal cancer，and multivariate Logistic regression analysis was used to further analyze the above One-way ANOVA analysis results. P<0.05 was statistically significant.

Among 420 elderly patients with colorectal cancer，96 cases were diagnosed with lung metastasis（22.86%）. CT findings of lung metastases showed multiple solid nodules with a diameter of less than 3cm，multiple and uniform enhancement. Univariate analysis showed that there were significant differences in primary tumor site，TNM stage，pathological type of primary tumor and CEA level between the two groups（P<0.05）. Multivariate logistic regression analysis showed that colorectal cancer，TNM stage Ⅲ，adenocarcinoma，CEA≥5 ng/ml were the risk factors for lung metastasis in elderly colorectal cancer.

Elderly patients with colorectal cancer have a high incidence of lung metastasis，with obvious CT features，and the main risk factors are colorectal cancer，TNM stage Ⅲ，adenocarcinoma and increased CEA levels. Clinical attention should be paid to these patients.