Abstract: Weathering effect can lead to the development of pores in rock material, which affects its engineering properties seriously. Therefore, studying the influence of weathering effect on the mechanical properties and anti-penetration properties of granite is of great significance to evaluate the damage effectiveness of penetration warheads and analyze the protection capability of underground facilities. The two kinds of granite with different weathering degrees were selected to systematically investigate their physical properties, static/dynamic compressive properties and anti-penetration properties with the experiment methods, such as the X ray diffraction (XRD) test, the static uniaxial compression test, the static triaxial compression test, the dynamic uniaxial compression test, the dynamic triaxial compression test and the two-stage light gas gun test. Finally, the results indicate that weathering effect can cause decrease of biotite and microcline, increase of porosity, loose internal structure, and obvious defects in granite, based on the X ray diffraction analysis technique. Besides, weathering effect also can lead to deterioration in granite’s compressive strength, weakened strain rate effect, and the shift of the failure mode from brittle failure to weak shear failure. Under static and dynamic triaxial compression, as for the two kinds of weathered granite, static and dynamic compressive strength rises significantly with confining pressure increasing meanwhile moderately weathered granite is more sensitive to confining pressure, compared with the slightly weathered granite. Under the condition of high-speed penetration, the speed varying from 873m/s to 1040m/s, there is a little difference in anti-penetration performance for the two kinds of weathered granite, in which case both of the non-dimensional penetration depths are generally no more than 3 times the length of the projectiles. Moreover, no obvious penetration trajectory zones exit in weathered granite targets while there are obvious crushed zones around the projectiles, the length of which can reach up to 5~8 times the diameter of the projectiles.