Objective: To explore a new method to measure the diaphragmatic contraction function by comparing the accuracy of the ultrasonic area method with excursion method. Methods: Seventy-eight healthy volunteers from Shengjing Hospital of China Medical University from May 2019 to April 2020 were selected in this study

and their general information was collected. Bedside ultrasound was used to measure the movement of the diaphragm and the change of the thoracic area during quiet breathing and deep breathing. Taking the deep inspiratory capacity (IC) of lung function as the evaluation standard

Spearman correlation test was used to compare the correlation between the two methods and IC. Results: There was no statistical difference in age

BMI and gender between the two measurement methods. There were significant differences in the correlation between the change of thoracic area and IC during quiet breathing (r=0.486

P=0.000) and the correlation between the change of diaphragmatic movement and IC during quiet breathing (r=0.245

P=0.031)

and there were also statistical differences in the correlation between thoracic area and IC during quiet breathing (r=0.424

P=0.000) and between diaphragmatic movement and IC during deep breathing (r=0.285

P=0.012). The correlation between the change of thoracic area and IC measured by ultrasonic area method was stronger than that measured by excursion method (the quiet breathing area difference>the quiet breathing diaphragmatic movement

the deep breathing area difference>the deep breathing diaphragmatic movement)

and the P value was significantly lower than that of the excursion method (the quiet breathing area difference<the quiet breathing diaphragmatic movement

and the deep breathing area difference<the deep breathing diaphragmatic movement). Conclusion: The area method is superior to the excursion method in the evaluation of diaphragmatic contraction function

and it’s more accurate to evaluate diaphragmatic contraction function combined with excursion method and diaphragmatic thickening rate.