Abstract: Objective To compare and evaluate the effectiveness and the clinic value between Ritodrine hydrochloride and Magnesium sulfate in the treatment of threatened premature labor. Methods We searched PubMed, Cochrane Library, CNKI, Wanfang, VIP, and references of the included studies up to February 2010. Studies involving treatment outcome of threatened premature labor using Ritodrine hydrochloride compared with Magnesium sulfate were included. Data were extracted and methodological quality was evaluated by two reviewers independently with designed extraction form. The Cochrane Collaboration’s RevMan 4.2 software was used for data analyses. Results A total of 9 studies involving 591 patients were included （Ritodrine hydrochloride, 308; Magnesium sulfate, 283）. The results of meta-analyses showed that Ritodrine hydrochloride comparing with Magnesium sulfate significantly more effective in the controlling of the uterine contraction,WMD=-2.97,95% CI（-4.18,-1.77）; more effective in the prolongation of gestational age, WMD=8.58, 95%CI（5.76, 11.40）; more effective in the weights of the newborns, WMD=0.36,95%CI（0.28,0.43）; equal in asphyxia of newborn, RD=-0.06, 95%CI （-0.14,0.02）. Conclusion Ritodrine hydrochloride treating for threatened premature labor is better than Magnesium sulfate in the treating period of suppression of contraction, prolongation of gestation for days and birth weights of newborns, asphyxia of newborn are equal in the both. But more attention should be paid to the untoward reaction.