Objective To assess the risk factors for adverse pregnancy outcome in the RFA selective reduction procedure for complicated multiple pregnancies and to compare the pregnancy outcomes between two radio frequency needle insert angles, abdominal and dorsal insert angle. Methods In order to retain at least one fetus, 145 pregnant women with complicated monochorionic multiple pregnancy chose radio frequency ablation to do selective reduction. Compare the procedure characteristics and pregnancy outcomes of the two different needle insert angles groups by SPSS 21.0. Results The RFA procedure in 145 complicated monochorionic multiple pregnancies were all conducted successfully, 116 cases through abdominal insert angle, and 29 cases through dorsal insert angle. Cox regression analysis indicated that the survival curve of fetal survival time interval after the procedure between the two needle insert angles were statistically different(P<0.001), with two significant predictors, cervical length (RR=0.969, P=0.043) and the gestational age before the procedure (RR=1.205, P<0.001) . Multivariable logistic analysis showed that compared to live birth at term, the risk of miscarriage,termination and IUFD were statistically higher when the cervical length was less than 35mm(P<0.001).Even though the survival rate was non-significant different within the indications(P=0.623), the pregnancy with live born fetus showed a higher trend in IUGR &TTT(90.9%) than other indications. Conclusion The interval between RFA to delivery specific survival curve showed a significant improvement with the abdominal needle insert angle compared with dorsal insert angle. The cervical length and gestational age before RFA procedure were two risk factors about the adverse pregnant outcome.