Inclusion Criteria:  Female aged 18-75 years (including 18 and 75 years, calculated based on the signing date of the informed consent) Histopathologically confirmed recurrent/metastatic cervical squamous cell carcinoma that cannot be radically treated by surgery, radiotherapy or chemoradiotherapy No prior systemic anti-cancer therapy for recurrent/metastatic disease According to RECIST v1.1 criteria, the patient must have at least one measurable lesion Able to normally swallow drug tablets The organ function level is good Willing to participate and able to comply with research programme requirements  Exclusion Criteria:  Has any malignancy <5 years prior to study entry. Known to have brain or meningeal metastasis Known to have autoimmune disease Received live vaccinations 4 weeks before randomization or during the study period