The invention relates to a calibration method for an optical fiber preform measurement device. A scanning laser light source and a photoelectric position detector are relatively positioned in parallelin a certain distance and are started; the scanning laser light source and the photoelectric position detector relatively move in a parallel interval direction, so that a laser beam scans the detection surface of the photoelectric position detector along a horizontal surface on the boundary of one side of the photoelectric position detector and finishes scanning till the boundary of the other side of the detection surface of the photoelectric position detector; relative displacement total length and the position sensing signal of the photoelectric position detector are independently recorded,and a relative displacement amount and the position sensing signal are compared to calculate the response degree of linearity of the photoelectric position detector; and finally, an accurate displacement response degree of linearity or position response coordinate curve is obtained. By use of the method, the problem that system testing accuracy is affected due to the change of the response degreeof linearity of the photoelectric position detector is solved, and meanwhile, the measurement length of the photoelectric position detector is increased.