1, prostate enlargement, the most common cause. At the beginning of the disease, it can just show thin urine line, weakness of urination and dribbling. 2, prostate cancer 3, bladder tumor 4, rectal cancer compression or invasion of the urethra 5, urinary tract infection 6, bladder or posterior urethral stones 7, diabetes mellitus caused by bladder vegetative neuropathy 8, other causes such as postoperative bed rest, hypokalemia, etc.