The single arm clinical study is to evaluate the efficacy and safety of an anti-PD-1 antibody (Toripalimab) combined with chemotherapy (docetaxel or nab-Paclitaxel) in patients with advanced gastric cancer who failed first-line treatment.

54 patients who meet the inclusion criteria will receive Docetaxel (60-75mg/m2, every 3 weeks) or nab-Paclitaxel （125mg/m2，every 3 weeks）combined with Toripalimab( 240mg,every 3 weeks）for 4-8 cycles until the disease progresses or intolerable toxicity.

Inclusion Criteria:

1. Ages 18-75
2. Written informed consent from the patient.
3. Pathologically diagnosed gastric or gastroesophageal junction adenocarcinoma (GEJ).
4. Failure of first-line chemotherapy with fluorouracil ，or adjuvant therapy with fluorouracil drugs, but the end of adjuvant treatment is less than 6 months.
5. Measurable disease as per RECIST 1.1 criteria.
6. Adequate organ and bone marrow functions.
7. Female subjects should agree to use a medically approved effective contraceptive during the study period and for up to 6 months after the study，and must undergo a serum-negative pregnancy test within 72hours before starting the study drug, and out of lactation;male subjects should agree to use medically approved methods of contraception during the study period and within 6 months after the end of the study period.
8. Performance Status(ECOG) 0-2.
9. Life expectancy >3 months.

Exclusion Criteria:

1. First-line treatment with Taxanes- containing drugs.
2. Patients with any history of known or suspected autoimmune disease with the specific exceptions of vitiligo, atopic dermatitis, or psoriasis not requiring systemic treatment.
3. Have received immunosuppressive drugs within 2 weeks before starting the study drug, excluding local glucocorticoids or systemic glucocorticoids<10 mg/day prednisone or other glucocorticoids of equivalent dose.
4. Patients with HIV-positive.
5. Patients with viral hepatitis (such as HBV（hepatitis B virus）, HCV（hepatitis C virus）), HBV-DNA> 2000IU/mL, and unwilling to receive antiviral treatment.
6. History of clinically-significant cardiovascular disease ，Liver diseases such as liver cirrhosis decompensated liver disease, and chronic active hepatitis; poorly controlled diabetes (fasting blood glucose (FBG)>10mmol/L); urine routine indicates urine protein ≥++, and 24-hour urine protein quantitative > 1.0g.
7. Clinically-significant pulmonary compromise, including a requirement for supplemental oxygen use to maintain adequate oxygenation.
8. History of (non-infectious) pneumonitis that required steroids or presence of active pneumonitis.
9. History of prior allogeneic bone marrow, stem-cell or solid organ transplantation.
10. Clinically-significant gastrointestinal disorders, such as perforation, gastrointestinal bleeding, or diverticulitis.
11. History of malignant tumors (except for skin basal cell carcinoma and cervical carcinoma in situ treatment with tumor-free survival for more than 3 years.
12. patients with uncontrollable seizures, or loss of insight due to mental illness.
13. History of severe allergies or specific constitution.
14. Participant in other clinical trials within 28 days before study treatment.