Ｏｂｊｅｃｔｉｖｅ　To evaluate the effectiveness of posterior and subcostal transversus abdominis plane(TAP) block in analgesia for patients undergoing cesarean delivery.　Methods　At the end of the operation, 100 cases of participants with cesarean delivery are randomized divided into two different group. Patients in group A (n=50) received an ultrasound-guided posterior TAP block using 20 ml of 0.375％ ropivaeaine on each side. Group B (n=50) underwent a subcostal TAP block with same solution. Patient controlled intravenous analgesia (PCIA) had also been applied. The resting and exercise VAS scores were evaluated at 2, 6, 12 h and 24 h after operation. The consumption of butorphanol within 24 h after operation, the number of successfully delivered doses within 24 h after operation were recorded. The rate of participants' satisfaction and the rate of adverse reactions were also recorded.　Results　The exercise VAS scores at 2,6,12 h after operation in group A [(0.8±1.0), (2.1±0.9), (2.0±0.9)] were significantly lower than scores in group B [(1.8±1.4), (4.3±1.9), (4.6±2.2)] (P<0.05). The consumption of butorphanol and the number of successfully delivered doses within 24 h after operation were also lower than in group B(P<0.05), while the rate of satisfaction were higher in group A(7.9±1.6) than in group B (7.1±2.3)(P<0.05). The incidence of adverse reactions was also significantly lower in group A than in group B (P<0.05).　Conclusions　Compared with the subcostal approach, ultrasound-guided posterior TAP could afford a better effectiveness in in analgesia for patients undergoing cesarean delivery.