Abstract： Objective To draw the distributional curve of fetal umbilicalartery systolic/diastolic(S/D) by measursing umbilical artery flow velocity waveforms(UmAFVW) using ultrasound in non-selective population. Methods The UmAFVW of 7599 cases of gestational women in 24～44 weeks were measured during 1996.1～1998.12, and the statistics of P50, P80, P85, P90, P97.5for every week was perfomed. Results The percentile was decreasing with pregnant progressing; the S/D ratio of P80<2.5 P97.5<3.0 after 37 week. Conclusions It is reasonable to use the relative percentile value of certain gestational week as an abnormal cutoff point in the non-selective population.