Bi4Ti3O12 thin films were deposited on Pt/Ti/Si(p-100) substrate by RF magnetron sputtering at room temperature, and crystallized in a RTA furnace at temperature of 675°C for 10 minutes. SIMS analysis identifies that bismuth content in the Bi4Ti3O12 thin film reduced slightly from the surface into a depth of approximately 200 nm. XRD patterns revealed (117) phase was dominated regardless the film thickness, and the intensity of the other peaks increased with the increase of film thickness. (200) peak became dominant when the thickness of films were greater than 680 nm. SEM observation showed that the grains were stripe plate-like, and the grain size increased with the increase of film thickness. Dielectric constant increased with the increase of film thickness, and kept around a certain value with the thickness ranging from 300 to 640 nm, then it rose again as the film thickness above 680 nm. The leakage current and electrical breakdown also strongly depended on the film thickness.