Abstract: Objective To evaluate the effect and it’s related factors of single-dose methotrexate（MTX）regimen for tubal pregnancy. Methods A retrospective observation study of 117 patients with tubal pregnancy who were treated with a single-dose protocol of 50 mg/m² of MTX injected intramuscularly was performed.The relationship between general features,clinical symptoms,serum human chorionic gonadotropin（HCG）,ultrasound parameters and treatment outcome was analyzed. Results The median serum HCG value of 117 patients with tubal pregnancy was 768.7 IU/L,and the success rate was 82.9%.The success rate was higher in paitents with prolonged menopause and vaginal bleeding（P＜0.05）.The success rate was higher in patients with low level of pretreatment serum HCG than in patients with high level of pretreatment serum HCG（P＜0.01）.The higher success rate was observed in patients with more than 15% decline of serum HCG from day 1 to day 4 and day 1 to day 7 after MTX therapy（P＜0.05 or P＜0.01）.The decline of serum HCG from day 4 to day 7 had no significant effect on the success rate（P＞0.05）.Conclusions MTX therapy is an alternative treatment for hemodynamically stable tubal pregnancy.Blood HCG level is the main factor related to the treatment effect.The natural history of tubal pregnancy is diverse.It is necessary to explore the detailed parameters and better cost-effective treatment recommendations.