In order to realize ultra-smooth polishing for the optics of 193 nm projection lens, a non-contact micro fluid jet ultra-smooth surfaces polishing method is introduced, and the material removal mechanism and ultra-smooth polishing effect are investigated. First, the material removal mechanism is studied by fluid dynamics simulation, which indicates that the shape of the remove function takes on W type through the analysis of the flow flied. Then the influence of the technological parameters on the polishing effect is analyzed by using orthogonal test. It is shown that the material remove rate increases as the entrance velocity and abrasive concentration increase, and decreases as the work distance increases, and the work distance has a great effect, which gives some directions for the choice of technological parameters in the experiment study. At last, one fused silica flat optical element is polished, and the surface roughness (root-mean-square) of the sample is improved from initial 1.02 nm to final 0.56 nm. It is shown that the micro fluid jet polishing technology can be used for optical element ultra-smooth polishing.