Abstract: The present invention discloses an angle adjusting structure for a Cartesian robot arm, comprising an angle adjusting element, a base, and a clamp. A motor transmission unit is disposed on the base, and an upper pulley, a lower pulley and a driving wheel are disposed on the base adjacent to the angle adjusting element. The driving wheel is connected to the motor transmission unit. The upper and lower pulleys clamp the angle adjusting element, and a drive belt is wound around peripheries of the upper pulley and the driving wheel. The clamp is secured to a face of the angle adjusting element opposite to the base, and a glue dispensing needle is disposed at one end of the clamp. The motor transmission unit rotates the driving wheel to drive the drive belt, so that the angle adjusting element is displaced and thus to change a glue dispensing angle.