A low temperature poly-silicon thin film preparation apparatus and a method for preparing the same are disclosed, the preparation apparatus comprises a substrate cleaning tank and an ozone generating device connected thereto, such that not only can blow off residual liquid on a surface of a glass substrate, but can also allow the glass substrate to directly contact the ozone, such that a silicon film on the surface of the glass substrate is more smooth and less impure, and an oxide film formed on the surface is more uniform since it contacts with the ozone at the first time after being cleaned by hydrofluoric acid, therefore the crystalline effect is more excellent.