Objective To determine the clinical efficiency and safety of 120W diode laser vaporization in the treatment of benign prostatic hyperplasia (BPH). Methods A total of 57 patients [aged 50 to 89 (71.7±7.1) years] with obvious bladder outlet obstruction and diagnosed as BPH were included in the study. They were treated with the HPD Laser (120W/980nm Ceralas D120, Germany) in our department. Their operation time, the prostate volume, International Prostate Symptom Score (IPSS), maximum flow rate (Qmax) and post-void residual urine (PVR) before and after operation were measured and compared. Results The surgery was successfully performed to all of the patients within a duration of (52.6±19.6) min. Their IPSS was decreased from 24.7±4.4 (15 to 32) before surgery to 3.5±1.2 (2 to 6) after surgery surgery. Their Qmax was increased from (6.7±3.4) ml/s (0 to 12ml/s) before surgery to (24.0±4.9)ml/s (17.8 to 31.2ml/s) postoperatively, and PVR was reduced from (77.2±45.7) to (5.1±7.7) ml. Significant differences were seen in above indexes. No death, blood transfusion, urinary incontinence or secondary operation was observed in the cohort. Conclusion Diode laser of 980nm with output power up to 120W is safe and effective in prostate vaporization for BPH, but quite expensive.