The non-uniformly distributed calcareous concretion among the oil shale in the Junggar basin of China has led to the difficulty in achieving the slope stability. This paper presents the numerical simulation of the behavior of oil shale with calcareous concretion via the Particle Flow Code (PFC2D) program based on the trial experimental test results. The critical parameters investigated in this research covered the size, distribution, strength, and number of the calcareous concretion. The following conclusions can be drawn based on the discussions and analysis: (1) the hard concretion always results in the high compressive strength of the specimen compared with that without concretion; (2) when the radius of the concretion size raised from 2.5 mm to 20 mm, the peak strength of tested specimens is approximately 50 MPa, whereas, the specimen with large concretion is much more ductile under compression; (3) the compressive behavior of tested specimens is similar even when the position of the concretion is variable; and (4) different from the specimens with only one concretion, these specimens contained two concretions featured with the double “X” failure mode. Meanwhile, the peak strength of the specimens with two hard concretions is about 2.5 times that of its counterparts with two soft concretions. The numerical simulation results are meaningful in guiding the design and analysis of the oil shale slope with the concretion.