Inclusion Criteria:  Patients who were diagnosed as esophageal squamous cell carcinoma by histopathology with at least one measurable lesion according to RECIST 1.1 criteria. Must have had progressive disease after previous treatment with PD-1 inhibitor ECOG score 0-2 The expected survival time is ≥ 12 weeks Previous permanent discontinuation did not occur due to adverse events associated with immunotherapy, or the immunotreatment-related adverse events recovered to ≤1 grade  Exclusion Criteria:  Had other active malignant tumors within 5 years before entering the study Had abnormal swallowing function or dysfunction of gastrointestinal absorption The first study drug treatment was less than 28 days or 5 half-lives (in terms of longer) from the last radiotherapy, chemotherapy, targeted therapy or immunotherapy Patients who have already received surgery within 28 days (biopsy for diagnosis is permitted) Pregnant or lactating women