Since jointed rock mass exists extensively in practical engineering, in-depth research on the effect of joint’s dip angle on rock strength and physical characteristics is of great significance to the stability of jointed rock mass projects. The influence of joints on sandstone’s strength and physical properties is investigated through triaxial loading test and acoustic test on intact rock specimen and jointed rock specimens with different joint angles under varying confining pressure. Results are concluded as follows (1) With the change of dip angle, the decay rate of longitudinal wave velocity of rock varies, reaching the maximum when dip angle is 60°. (2) The elastic modulus of intact rock is the largest, followed by those of jointed rock specimens with 90° dip angle, 30° dip angle, and 60° dip angle. (3) Given the same dip angle, the peak strength of rock increases with the increase of confining pressure; while under the same confining pressure, the peak strength of rock specimens displays obvious anisotropy with the change of dip angle. (4) The cohesion of jointed rock specimens changes in a U-shape curve with varying dip angle, and reaches the minimum when dip angle is 60°; the internal friction angle increases with the increase of dip angle. In conclusion, joints have remarkable influence on the strength, deformation, and physical properties of sandstone. In particular, the influence reaches the maximum when joint’s dip angle is 60°.