To study the uniaxial compression performance of rock masses with regular dentate discontinuities, uniaxial compression tests and Particle Flow Code (PFC) numerical simulation are conducted on cement mortar specimens, and the combined effects of dip angle γ, undulation angle β, and the number of undulating structures n of cracks on the compressive strength and crack propagation in the specimens are studied. The experimental and numerical simulation results showed that when n and β remain unchanged, the uniaxial compressive strength of the specimens peaks at a γ of 90°. When γ and β remain unchanged, the compressive strength of the specimens with regular dentate discontinuities decreases with an increase in n. When n and γ remain unchanged, the compressive strength of the rock mass specimens containing dentate discontinuity decreases with an increase in β. Almost all of the new cracks in the specimens initiate at the tip of the prefabricated cracks, and the failure characteristics of the specimens are mainly tensile fractures accompanied by a few shear fractures. When β and n remain unchanged, and γ is 45°–135°, the cracks in the dentate discontinuous rock mass propagate straight along the end of the prefabricated crack and finally vertically. In addition, when γ and n remain unchanged, the crack propagation of rock mass with β ≤ 60° is abundant. Moreover, when γ and β remain unchanged and n < 4, the crack propagation is abundant, and shear cracks are initiated at the edge of the specimens far from the prefabricated crack.