Barium titanate (BaTiO3) powders with particle sizes of 30～50 nm were prepared from barium stearate, titanium alkoxides and stearic acid by stearic acid-gel method. Dispersing the agglomerate of BaTiO3 nanoparticles into poly(amic acid) solution followed by curing led to the formation of polyimide hybrid films. The hybrid films were transparent and well distributed with BaTiO3 nanoparticles when the BaTiO3 content was less than 1 wt%. Highly loaded hybrid film containing 30 wt % BaTiO3 was tough, had a smooth surface and possessed much higher dielectric and piezoelectric constants than the parent polyimide.