A study of Raltitrexed plus Docetaxel versus Docetaxel as second-line chemotherapy in subjects with Gastric Cancer.The purpose of this study is to compare the activity of Raltitrexed plus Docetaxel versus Docetaxel as second-line chemotherapy in subjects with gastric carcinoma by estimating progression free survival (PFS) in each treatment arm.

Inclusion Criteria:

1. Signed informed consent form
2. Performance Status- Eastern Cooperative Oncology Group (ECOG) 0-2;
3. Histologically or cytologically confirmed gastric cancer;
4. The first-line chemotherapy failure (required containing 5-fluorouracil)
5. At least have one measurable disease(according to RECIST, Response Evaluation Criteria in Solid Tumors )
6. Life expectancy of at least 3 months;

Exclusion Criteria:

1. Received any prior treatment including Raltitrexed;
2. Active or uncontrolled infection;
3. Concurrent treatment with an investigational agent or participation in another therapeutic clinical trial;
4. Pregnant or lactating women.