Objective? To investigate the dynamic changes and clinical significance of serum LDH in patients with malignant tumor 3 months before death. Methods? The dynamic changes of serum LDH in 148 patients with malignant tumor who died in Nanjing Red Cross Hospital from January 2018 to July 2020 were retrospectively analyzed. Results? The closer to death，the higher the level of LDH in patients with malignant tumor.The LDH level of patients with liver metastasis was significantly higher than that of the whole population in the three months before death，and it was significantly higher than that of patients without liver metastasis. Conclusion? The serum LDH level of patients with malignant tumor is on the rise before death. The change of LDH can be used as a reference index for prognosis judgment，and the high LDH value can be used to predict the diagnosis of liver metastasis.