The invention discloses a three-degree-of-freedom posture adjusting device and relates to the field of multi-degree-of-freedom lathe tool adjustment. The three-degree-of-freedom posture adjusting device comprises a base and an adjusting connecting plate. A ball-head screw is fixedly connected to the base. The lower portion of the ball-head screw is movably connected with a ball head locking pad. The adjusting connecting plate is connected with the ball head locking pad through connecting screws. The outer sides of the connecting screws are slidably connected with an upper locking plate. A ball-head connecting screw matched with the adjusting connecting plate is in threaded connection with the upper locking plate. The front and rear sides of the base are both in threaded connection with horizontal angle adjusting screws matched with the adjusting connecting plate. The left side of the adjusting connecting plate is in threaded connection with a roll angle adjusting screw. The front sideof the adjusting connecting plate is in threaded connection with a pitch angle adjusting screw. The three-degree-of-freedom posture adjusting device can implement three-angle adjusting of pitch, rolland horizontal rotary turning by adjusting the screws in different positions, thereby being suitable for small-angle slight adjustment of accurate alignment, convenient to use and easy to adjust.