Improperly performed urethral dilatation can lead to perforation, organ damage, or even aggravate the lesion of urethral stricture, the spread of infection, or even sepsis and life-threatening. Therefore, the following cases should be contraindicated: 1, acute inflammation of the urethra and prostate, or excessive urethral discharge, urethral probe examination, which can spread the inflammation or cause urethral fever; but for urinary retention complicating acute upper urinary tract infection, fever, after the failure of indwelling catheter, urethral probe examination or dilation can be used, and the catheter should be left in place to drain after surgery; 2, suspected urethral tumor; 3, urethral injury, mainly posterior or bulbous urethra injury due to pelvic fracture or perineal riding injury, urethral probe examination can aggravate the injury, cause perforation, false passage or occurrence of hemorrhagic shock; 4. Those who have urethral fever after each urethral dilatation. Bacteraemia is a common complication and is frequent in patients with urinary tract infections. Deaths due to bacteraemia after urethral dilatation have been reported and should be noted. In any type of urethral stricture, if regular weekly urethral dilatation for more than 3 to 6 months does not yield the desired results, a change to another treatment should be considered.