In order to achieve ultra-precision polishing of the workpiece surface, a UV-induced nanoparticle colloid jet processing system was established. The hydrodynamic characteristics, polishing process, and ultra-smooth surface morphology of the UV-induced nanoparticle colloid jet processing of two nozzles with different cavity structures were studied. Firstly, conical and cosine opto-hydraulic coupling nozzles were designed according to the requirements of opto-hydraulic coupling. Then, three-phase flow simulation of non-submerged jet was carried out for two kinds of opto-hydraulic coupling nozzles, and the flow track and flow field distribution of nanoparticles were compared and analyzed. Next, light-coupled colloid jet polishing experiments were carried out on the same single crystal silicon workpiece with two kinds of nozzles using titanium dioxide nanoparticle colloid as polishing fluid. Finally, the surface before and after polishing was characterized and compared. The results show that the flow velocity (20.73 m/s) and dynamic pressure (2.5 MPa) obtained by the cosine nozzle are higher than that of the conical nozzle with flow velocity (7.12 m/s) and dynamic pressure (0.2 MPa). The average residence time of nanoparticles in the cosine nozzle (0.00 5 s) is shorter than that of the conical nozzle (0.023 s). Under the same polishing parameters, the surface roughness (Rq 0.810 nm, Ra 0.651 nm) of the workpiece polished by cosine nozzle is lower than that of the conical nozzle. Using the cosine nozzle in UV-induced nanoparticle colloid jet processing can result in lower surface roughness than with the conical nozzle.