The invention discloses a polar coordinate type deviation measuring device and belongs to the technical field of measurement equipment. The device comprises a spot capture device, a control unit, an underframe and a swing arm, wherein the lower portion of the swing arm is hinged to the underframe, gear teeth with the hinging position being a rotating center are arranged at the tail end of the swing arm, a stepping motor is arranged in the underframe, the stepping motor drives the swing arm to rotate in a circular plane with the swing arm being a radius in a gear transmission mode, a linear guide rail is arranged on the swing arm, a radial moving system used for driving the spot capture device to move along the guide rail is also arranged on the swing arm, the spot capture device comprisesa spot projection screen and a spot induction unit located behind the spot projection screen, and the stepping motor, the radial moving system and the spot capture device are all connected with the control unit. The device is simple in structure, low in cost and convenient to use, overcomes the defect that it is difficult to perform large-range spot capture in the prior art, and is an important improvement to the prior part.