Abstract: MMT/ TiO₂ / PI hybrid films with various nano-filler content s were successfully prepared via in-situintercalation and sol-gel process. The molecule st ructure , fracture morphology and thermal properties were investigated by FTIR , UV-Vis , SEM and TGA , respectively. The mechanical properties at cryogenic temperature (77 K)were studied as a function of TiO₂ mass f raction. The result s show that the MMT and TiO₂ particles are welldispersed in the polyimide mat rix. Td of hybrid films is higher than that of the pure PI film. At 77 K, the tensilest rength of TiO₂ / PI hybrid film decreases with the increase of TiO₂ mass f raction while that of MMT/ TiO₂ / PIhybrid film increases with the increase of TiO₂ mass f raction and reaches the maximum when the TiO₂ mass f ractionis 2 %. The elastic modulus increases with the increase of TiO₂ mass f raction but the elongation decreases with theincrease of TiO₂ mass f raction.