Cu-filled isotropically conductive adhesive/SiO2 composites were prepared by direct-blending modified SiO2 into Cu-filled ICAs. The effects of different contents of SiO2 on the mechanical property were sdudied in this paper. The infrared spectra of the cured product between epoxy resin and imidazole was obtained with FT-IR. The surface morphology of the composite and its fractured surface after tensil test were observed by scanning electron microscope(SEM). In addition, energy dispersive spectrometry(EDS) was applied to analyze the distribution of Si in the adhesive layer. Experimental results showed that a small amount of SiO2 powders could evenly distribute in the Cu-filled ICAs, and as a reslut the mechanical property of Cu-filled ICA/SiO2 increased dramatically with the addition of SiO2. The best shear strength of the composite could reach up to 16.1MPa and 36.4% higher than the ICAs without addition SiO2 when the content of SiO2 was 3%.