With the development of ISRU Technology, lunar soil has become an important kind of building material for lunar base. Although the particle shape of lunar soil is extremely irregular, the non-linear mechanical property of lunar soil particles is rarely researched. In this paper, the relationship between the displacement and the contact force of lunar soil particles were researched. First, a series of experiments on normal mechanical properties of lunar soil particles based on the high-precision micro-operation test bed were carried out. Second, a contact model for irregular lunar soil particles was established. The irregular particles are equivalent to spherical particles, and an equivalent algorithm based on piecewise function fitting was proposed. Finally, a series of simulation were carried out to verify the equivalent algorithm in the discrete element method software EDEM. The results provided a solid theoretical basis for the calculation of contact forces between irregularly shaped lunar soil particles. (C) 2019 Elsevier B.V. All rights reserved.