Inclusion Criteria:  Aged 18-75 years old; ECOG physical status score 0-1 points (within 3 days before starting treatment); Expected survival period ≥ 3 months; Basically normal functions of major organs; Pathologically confirmed metastatic gastric cancer or adenocarcinoma at the gastroesophageal junction with no chance of radical surgery, accompanied by liver metastasis or simple liver metastasis; No previous medical treatment; If neoadjuvant or adjuvant chemotherapy has been performed before and after surgery, recurrence can be defined as first-line therapy only after drug withdrawal for at least six months; HER2 negative. HER2 negative definition: IHC (0 or 1+), or IHC (2+) but negative for FISH (HER2:CEP17<2 with mean HER2 copy number <4.0 signals/cell); Measurable lesions assessed according to RECIST1.1; Able to swallow pills normally.  Exclusion Criteria:  Those who are allergic to thalidomide; Pregnant or lactating women; Severe mental illness; Those who cannot take medication or follow up as planned; During the trial period and within 3 months after the trial, the subjects and their partners are not willing to use contraception; Participants in other clinical studies 3 months prior to the trial； Patients who are financially well off and willing to use immune checkpoint inhibitors.