Lattice Boltzmann method(LBM) was introduced into the seepage characteristic analysis of asphalt pavement crack. The mesoscopic seepage numerical model of complex single fracture surface under pressure gradient and corresponding calculation program were established, which were validated by the cubic law of smooth plate crack seepage. Based on the model and program, the influence of roughness and tortuosity of asphalt mixture crack surface on seepage was discussed respectively. The results show thatthe crack seepage deviates obviously from the cubic law with the increase of relative roughness. With the increase of the tortuosity, the crack seepage is proportional to its -38327 power. Therefore, a permeability coefficient tester with applicable confining pressure side rubber membrane is developed, and the results are compared and analyzed through laboratory tests.The modified formula suggested is more accurate and reasonable, which can provide reliable basis for infiltration rate of pavement and valuable reference fordrainage design.