The prostate is an irregular, spherical, three-dimensional structure. The normal volume for a mature male is about 15-20 ml. For the volume and morphology of the prostate, the data from transrectal 3D ultrasound is the most accurate, scientific, and credible. The volume data of the prostate gland obtained from ordinary lower abdominal ultrasound as well as anal finger examination can only be two-dimensional parameters, which are inaccurate and unscientific. 1, etiology: men have varying degrees of hyperplasia after the age of 45. The corresponding clinical symptoms can occur. The prostate gland is mainly regulated by androgens and the role of various growth factors, and an imbalance in these roles may be an important cause of prostate enlargement. 2, pathological changes are mainly prostate glandular hyperplasia and interstitial hyperplasia. The prostate gland is rich in alpha-adrenergic receptors, and activation of these receptors causes the smooth muscle in the area to contract, increasing the resistance of the prostate urethra; during transrectal ultrasonography, it can be seen that the prostate gland increases to several, ten or even tens of times its normal size. In contrast, prostate cancer mainly occurs in the peripheral zone of the prostate (ectopic prostate), which can be seen as nodules or low signal echogenicity in the peripheral zone of the prostate during transrectal ultrasound. The most accurate way to examine prostate enlargement is through transrectal ultrasound, which is currently the preferred method to evaluate the volume and structure of the prostate internationally. In addition, rectal examination of the prostate, serum prostate-specific antigen (PSA), and MRI of the prostate can help further evaluate the risk of prostate cancer, while urodynamic examination and free flow rate measurement can help determine the severity of obstruction or identify non-prostatic factors causing bladder outlet obstruction. By understanding more about prostate enlargement can better help in diagnosis and timely treatment.