• 18-75 years old, both sexes.

• Esophageal squamous cell carcinoma confirmed by histology or cytology with locally advanced unresectable or distant metastasis (according to AJCC 8th edition).

• ECOG PS score of 0 \

• Expected survival ≥3 months.

• Patients who have failed first-line immunotherapy combined with chemotherapy.

• At least one measurable or unmeasurable lesion according to RECIST V1.1 criteria (subjects with intracranial lesions alone were excluded from this study).

• Ability to swallow investigational drugs .

• The functional level of the organ must meet the following requirements. (1) ANC≥1.5×109/L; (2) PLT≥100×109/L; (3) Hb≥90 g/L; (4) Serum albumin ≥30 g/L; (5) TBIL≤1.5×ULN; ALT and AST≤2.5 x ULN; For patients with liver metastases, ALT and AST≤5×ULN; (6) Cr ≤1.5×ULN, or creatinine clearance ≥50mL/min as calculated by the Cockcroft-Gault formula; (7) Patients with urinary protein ≥++ should undergo further 24-hour quantitative detection of urinary protein, and the detection result should be\<1.0g.

• Within 7 days prior to enrollment, women of reproductive age must confirm a negative serum pregnancy test and consent to use effective contraception during the study drug use period and within 2 months after the last dose.

⁃ Subjects voluntarily participate in the study after fully informed consent and sign the informed consent.