Immunotherapy is a newer therapeutic tool for treating liver metastasis of small cell lung cancer, which has a better effect on some patients, but its final therapeutic effect depends on a variety of factors, such as the patient’s physical condition. Small cell lung cancer (SCLC), which accounts for about 15% of all lung cancers, is a highly aggressive neuroendocrine tumor, with smoking as the main high-risk causative factor, rapid growth, high metastatic rate and poor prognosis. Its clinical characteristics are good initial response to chemotherapy and radiotherapy, but the strong proliferative ability of cancer cells leads to high recurrence and early metastasis rates. The immune system is the self-protection barrier of the human body. The human body identifies and removes cancerous cells through “immune surveillance” to fight against tumor cell invasion and maintain the normal and orderly operation of the organism. These include programmed cell death protein 1 (PD-1) inhibitors and programmed death ligand 1 (PD-L1) inhibitors, such as atilizumab and divalizumab. Studies have shown that the addition of atilizumab and doxorubicin to chemotherapy can bring survival benefits to patients with extensive stage SCLC, with the overall survival time extended by 2 months in the atilizumab group and 2.7 months in the doxorubicin group. It is recommended to go to a regular hospital to evaluate the condition, follow the doctor’s instructions to cooperate with the treatment, and choose the appropriate treatment plan to avoid delaying the condition. Please strictly follow the doctor’s instructions, do not self-medication.