Objective To study the clinical effects of patient controlled epidural analgesia on the duration of labor, mode of delivery, and to evaluate the safety and feasibility of patient controlled epidural analgesia (PCEA). Methods One hundred primigravidas at term without contraindications for vaginal delivery and epidural analgesia were assigned into two groups, observation group (OG) and control group (CG), 50 each, using case control method. When the cervical dilations of patients reached 3 cm in the OG group, they received 0.1% ropivacaine plus sufentanil 0.5 mg/L. The PCEA setting was 6 ml/h-8 ml/h background dose, 5 ml for PCA-demand dose, 15 min lockout interval. The control group was treated with routine managements without PCEA. The duration of labor stages, mode of delivery, use of oxytocin and instrumental delivery were observed and documented. Visual analogue score (VAS) of pain was also recorded when cervical dilations were at 3(T1), 8 (T2), and 10 cm (T3), as well as at the end of the second stage (T4). Results The duration of the first stage of labor was shorter (P<0.05) in the OG group(658±46) than in the CG group（696±48) . The rate of score was lower (P<0.001) in the OG group than in the CG group .The VAS of OG group at T2 、T3、T4 were (1.3±0.5)， (1.2±0.7)，and (1.9±0.6) respectively；While the VAS of CG group at T2 、T3、T4 were(7.3±0.7), (6.5±1.2), and (6.9±2.8) respectively. When cervical dilation more than 3 cm, however, the dose of oxytocin used for parturients in the OG(60%) group was higher(P>0.05) than in CG group (30%). There were no statistical differences with maternal bleeding and neonatal APGAR scores between the two groups. Conclusions Ropivacaine 0.1% plus sufentanil 0.5 mg/L used in PCEA for labor pain was effective. PCEA reduced the duration of first stdge labor and the rate of cesarean section.