Abstract: In order to study the static damage characteristics of the tri-cracked rock, the discrete element numerical simulation software PFC^2D and model tests were used to analyse the peak strength, stress-strain curve and crack propagation characteristics of the tri-cracked rock, and to verify the feasibility of the discrete element numerical simulation method. To this end, the mechanical response mechanism of the three-cracked rock under uniaxial compressive loading was analysed by sequentially varying the horizontal envelope pressure and crack length of the rock. The results of this study show that:(1) The intermediate transverse crack has a greater effect on the peak strength of the cracked rock, and the intermediate vertical crack has a smaller effect on the peak strength of the cracked rock. (2) The stress concentration at the crack tip was the first to appear during the loading process, and finally two main cracks at about 70° were formed through the three precast cracks. (3) The uniaxial compressive strength of the tri-cracked rock first increases and then decreases as the surrounding pressure increases. (4) As the crack length increases, the uniaxial compressive strength of the tri-cracked rock decreases.