Abstract: A laser resectoscope for minor caliber includes a water back system, a water inlet system, a laser sheath system, an observation system. The water back system includes a water return pipe and a water outlet structure. The water inlet system includes a water inlet pipe and a water inlet structure. The laser sheath system includes a laser sheath, an optical fiber and a laser head. The observation system includes a mirror tube and an eyepiece. It is increased for the water return of the laser resectoscope, and the laser resectoscope in F24 can be used to meet the surgical requirements of the conventional laser resectoscope in F26 clinically.