To understand the splitting-tensile behavior of internal cross-cracks in rock, discrete element splitting simulation tests were carried out by using a particle flow code (PFC^2D) based on the physical and mechanical parameters of rock obtained from laboratory tests. The results show that the tensile strength of specimens with pre-fabricated cracks is lower than that of intact specimens. When the angle between the main crack and the loading direction ranges from 0° to 60°, the peak strength of specimens decreases with the increase of the secondary crack angle; when the angle ranges from 60° to 90°, the peak strength increases with the increase of the secondary crack angle. In general, the tensile strength of specimens follows the rule that the larger the angle difference between the main and secondary cracks, the smaller the tensile strength. Under splitting loading, pre-fabricated cracks do not change the loading mode of specimens but only reduce their bearing strength. Micro-cracks in cross-crack specimens are dominated by tensile micro-cracks, which initiate near the tips of pre-fabricated cracks, propagate toward the loading ends and coalesce with increasing load, resulting in specimen failure. Irreversible transformation of internal energy occurs during rock failure. When the loading reaches the storage limit of elastic strain energy, the elastic strain energy is rapidly converted into dissipated energy for micro-crack initiation and propagation as well as particle movement. A large number of acoustic emission events occur simultaneously, and the number of micro-crack increases exponentially.