Two important conditions must be present for BPH to occur: aging and a functioning testicle. Domestic scholars investigated 26 elderly Qing dynasty eunuchs and found that the prostate gland had become completely inaccessible or significantly atrophied in 21 of them. However, the specific mechanism by which BPH occurs is unclear and may be caused by a balanced disruption of epithelial and mesenchymal cell proliferation and apoptosis. Associated factors are: androgens and their interaction with estrogens, prostatic mesenchymal-adenoepithelial cell interactions, growth factors, inflammatory cells, neurotransmitters and genetic factors. Prostatic hyperplasia leads to prolongation, pressure deformation and narrowing of the posterior urethra and increased urethral resistance, resulting in a series of changes in bladder function and the upper urinary tract. Due to the increase in bladder pressure, compensatory hypertrophy of the bladder forcing muscle, instability of the forcing muscle and reduced bladder compliance occur; if the obstruction is not lifted for a long time, the forcing muscle loses its compensatory capacity. The thickening of the bladder forceps can cause the ureteral bladder wall segment to lengthen and stiffen, resulting in mechanical obstruction of the ureter; after the bladder loses its compensatory capacity, the ureteral bladder wall segment can be shortened again, and coupled with the increase in bladder pressure, ureteral reflux can occur, eventually leading to hydronephrosis and renal function impairment. Male patients over 50 years of age who exhibit the following urinary tract symptoms should first consider the possibility of prostatic hyperplasia (BPH).