Field assisted quantum tunneling composite (FAQTC) is a unique pressure-sensitive material with the advantages of large resistance change range under external force, easy preparation and excellent mechanical properties. In this paper, with attentions to the pressure-sensitivity of the FAQTCs, the effects of silicon rubber matrix, diameter and dosage of nickel particles as well as magnetic field treatment are systematically investigated. The reproducibility of the pressure-sensitivity of the FAQTCs under cyclic load is explored. Based on Cotton's equation and Burger's model, the descriptions of stress relaxation behavior and electrical resistance relaxation behavior of the composites under static compressive loading are given respectively. The results show that external magnetic field during curing process allows better adjustment of the pressure-sensitivity of the FAQTCs with fewer nickel particles. The increase of the dosage of nickel particles can improve the stability and reproducibility of the pressure-sensitivity of the composites. Electrical resistance relaxation behavior of the composites is partly controlled by the stress relaxation behavior. Moreover, based on the theory of percolation conduction, the mechanism of the pressure-sensitivity of the FAQTCs under uniaxial load is discussed and further qualitatively explained by adopting effective conducting path model. Finally, on the basis of this model combined with quantum tunneling effect, a mathematical model describing the pressure-sensitivity of the composites is established, which can well describe the pressure-sensitivity of the composites. (C) 2017 Elsevier Ltd. All rights reserved.