Objective To detect the change rule of uterine artery blood flow resistance parameter in early-middle pregnancy of normal pregnant women, and provide the basis to the prediction of related diseases. Methods The resistance index (RI) and pulsation index (PI) of uterine artery on both sides of the normal pregnant women at 11-14 weeks and 18-20 weeks of gestation were detected, and the change rule of these parameters in the process of early to middle pregnancy was observed. Results PI of the left side uterine artery was (1.56 ±0.518) in the early pregnancy, and reduced to (1.13 ±0.424) in the middle pregnancy. RI of the left side uterine artery reduced from (0.71 ±0.112) to (0.61 ±0.109). PI of the right side uterine artery was (1.50 ±0.518), and reduced to (1.01 ±0.391) in the middle pregnancy. RI of the right side uterine artery reduced from (0.70 ±0.106) to (0.59 ±0.114). There were significant differences in uterine artery blood flow resistance parameters (PI and RI) between early pregnancy and middle pregnancy (P < 0.05). The uterine artery blood flow resistance parameters (PI and RI) had no significantly different between left and right sides at early pregnancy (P > 0.05), but had significantly different in middle pregnancy (P < 0.05). Conclusions The uterine artery blood flow resistance parameters are significantly reduced from early pregnancy to middle pregnancy.