Abstract: In order to develop the composite film with better force sensitive characteristic, nano Fe50Ni50 powders whose particle size was about 100 nm were prepared by liquid phase reduction method firstly, and the nano powders were mixed and dispersed with butyl rubber(IIR) by liquid phase mixing dispersing method. Then, the nano Fe50Ni50 powders/IIR composite films whose powders were well dispersed and content was 65wt% were obtained by mechanical mixing and pressing. Finally, the force-sensing characteristics of nano Fe50Ni50 powders/IIR composite films were investigated under the conditions of continuous uploading/downloading speed was 0.10 mm/min and test frequency was 1 kHz. The results show that liquid phase mixing dispersing method can make the Fe50Ni50 powders achieve uniform dispersion effect at nano-scale in the composite films. When compressive stress is 0.20-0.90 MPa, the thicker the film is, the larger its standard deviation is, and the worse the force sensitivity stability is. With compressive stress increasing, impedance of the film which thickness is 185μm decreases linearly approximately during uploading period, and force sensitive degree is stable in range of 40-60, the standard deviation is about 1-2. The conclusions obtained show that the prepared film has excellent force sensitive characteristic when the compressive stress is 0.20-0.90 MPa.