Purpose To explore the clinical value of reducing the incidence of reflux and improving patients' comfort by low pressure contrast injection during transvaginal ultrasound real time three-dimensional hysterosalpingo-contrast sonography (TVS RT-3D-HyCoSy).Materials and Methods Data ofTVS RT-3D HyCoSy using low pressure contrast injection of 498 infertile women were analyzed.The peak pressure,the incidence of reflux and adverse reactions were recorded.Compared these parameters between bilateral tubals.Results The peak pressure in patency,partially patency and fully obstructed of bilateral tubals were (22.47±5.96) kPa,(37.24±8.83) kPa and (44.64±7.73) kPa.There was significant difference among the three groups (F=70.35,P＜0.05).Among all 498 patients,the incidence of reflux was 26.31％.The incidence in patency,partially patency and fully obstructed of bilateral tubals were 18.00％,30.21％ and 43.59％.There was significant difference among the three groups (x2=15.59,P＜0.05).Different degrees of adverse reactions were 88.96％,10.64％ and 0.4％.Conclusion By using low pressure contrast injection during HyCoSy,the incidence of reflux can be reduced and examination comfort can be improved.