A two-dimensional Particle Flow Code (PFC2D) was applied to simulate sand liquefaction behavior induced by cyclic loading. The numerical sample was prepared with 4061 discs with its particle size distribution similar to Fujian Standard sand. Based on the theory of strain-controlled undrained cyclic triaxial test, a constant volume numerical test was carried out under cyclic loading with uniform strain amplitude. The macroscopic responses of the sample were obtained and the variation of average coordination number under cyclic loading was analyzed. The effects of cyclic strain amplitude and confining pressure on liquefaction resistance were further analyzed in numerical simulations. It was found that the numerical tests reproduced the general characteristics of liquefaction behavior of saturated sand under cyclic loading. The effects of cyclic strain amplitude and confining pressure on the liquefaction resistance of the numerical sample were comparable with reported experimental results.