Abstract: In order to prepare polymer piezoresistive materials with good flexibility, carbon black/polypropylene-poly(styrene-ethylene/butylene-styrene) (CB/PP-SEBS) composites were fabricated through melt blending method. The effects of CB content on the dielectric properties and piezoresistive properties of CB/PP-SEBS composites were investigated. The results indicate that the dielectric constant, dielectric loss and electrical conductivity of CB/PP-SEBS composites are all enhanced with the increasing of CB content. The electrical conductivity percolation of CB/PP-SEBS composites occurs when the CB content is 12.2wt%. Owing to the external force destruction of conductive network of CB, the electrical resistivity of CB/PP-SEBS composites increases with the strain increasing during the elastic deformation process of CB/PP-SEBS composites. The periodic piezoresistive measurement results indicate that the electrical resistivity of CB/PP-SEBS composites varies periodically with strain in the elastic deformation region. The results could give some experience for the preparation of polymer piezoresistive materials with stable resistance variation.