To explore the clinical value of real-time shear wave ultrasonic elastography in diagnosing the depth of infiltrating muscularis of endometrial cancer. Seventy-one patients with stage I endometrial cancer infiltrating the myometrium and 37 patients with normal physical examination were enrolled and divided into three groups: endometrial cancer superficial muscle infiltration group, endometrial cancer deep muscle infiltration group, and normal control group. After completing 2-dimensional ultrasound examination, each patient switched to the real-time shear wave elastography mode to measure the elasticity values Emax, Emean, and Esd. For control group, comparison of elastic modulus values between superficial muscular layer near the intimal surface and the deep muscular layer near the serosa surface showed no difference (P > 0.05). For endometrial cancer superficial muscular infiltration group, significant difference was found regarding the elastic modulus values of infiltrated muscular layer and uninfiltrated muscular layer (Emax and Emean) without difference for Esd (P > 0.05). A significant difference of elastic modulus was observed between control group and deep myometrial infiltration group (P < 0.05) without difference of Emean or Emax but with difference of Esd. The accuracy in diagnosing muscular layer infiltration was 78.9% for Emax cutoff and 82.5% for Emean cutoff. The rate of using Emax ≥32.22 kPa or Emean ≥27.54 kPa as the ultrasound standard for diagnosing myometrium infiltration was 92.9%. The accuracy for the diagnosis of muscular layer infiltration was 96.1% for Emax cutoff, 94.1% for Emean cutoff and 86.3% for Esd cutoff. Real-time shear wave elastography is helpful to determine the depth of infiltrating myometrium of endometrial cancer. © 2020 American Institute of Ultrasound in Medicine.