Objective High frequency ultrasound was used to measure the inter-rectus distance at four reference points in nulliparous women. Methods A total of 106 healthy nulliparous female volunteers who underwent physical examination in our hospital from July 2019 to October 2019 were selected, and the BMI≤30kg/m2. High frequency ultrasound was used to measure the IRD at four locations, namely, 3cm above the umbilicus, at the umbilicus, 2cm below the umbilicus and 3cm below the umbilicus in supine position and abdominal curling position. The reference range of IRD was calculated by percentile method, and the relationship between IRD and age, height, weight and BMI index were analyzed. Results The normal range of IRD at rest was as follows: 3 cm above umbilicus was 4 ~ 15 mm, umbilical level was 5 ~ 20 mm, 2 cm below umbilicus was 0 ~ 7 mm, and 3 cm under umbilicus was 0 ~ 3 mm. Correlation analysis showed that IRD had no correlation with age and height, but had weak positive correlation with body weight and BMI. Conclusion In this study, high frequency ultrasound was used to establish the normal range of IRD in nulliparous women, which provided the basis for the diagnosis of diastasis recti. IRD was weakly positively correlated with body weight and BMI.