A light driven micro-rotor is a useful telecontrolled device free of mechanical contact for power supply. However, low efficiency in converting light to mechanical power detracts from its advantages because it incurs a high power consumption that might result in unwanted effects. For a systematic study on conversion efficiency, we designed a turbine-like micro-rotor and made a quantitative analysis by computational fluid dynamics and semiclassical optics. Much larger in size than those ever reported, our rotor could rotate at over 500 r/min. Denoted by average angular momentum transfer, its conversion efficiency was experimentally determined as high as 34.55 ℏ/photon.