Abstract: Objective:To explore the application value of power doppler ultrasound in estimating the tocolysis effects of threatened abortion.Methods:One hundred and forty-seven threatened abortion patients and 150 normal pregnant women were set as observation group and control group, respectively.The observation group were treated with progesterone tocolysis by intramuscular injection, the progesterone level and power doppler ultrasound in observation group were detected at the first day and after 1 week of admission.The relevant examination index and success rate of tocolysis between two groups were compared.Results:The VI, FI and VFI in observation group at the first day and after 1 week of admission were significantly higher than those in control group, and the increasing extent of which in observation group were significantly higher than that in control group(P<0.01).After tocolysis treatment in observation group, cure in 99 cases, good effect in 37 cases and invalid in 11 cases were identified, and the total effective rate was 92.52%.Conclusions:The power doppler ultrasound can accurately assess the placental blood perfusion, auxiliarily diagnosed and treated the threatened abortion and evaluate treatment effect.