In this paper we demonstrate a new technique in which we use the portable alignment device of an off-axis parabolic mirror optical axis adjustment and the CCD camera to rapidly and accurately align the optical axis of an off-axis parabolic (OAP) mirror. In this method the optical axis of an OAP mirror is made parallel to the "five incident parallel laser beams" in the plane of incidence, by checking direction of these five reflected laser beams and changing the height and orientation of the OAP mirror. The CCD camera uses to measure the best focus and minimum spot diameter of the OAP mirror. This fast aligning method for finding the optical axis of an OAP mirror can measure the deviation of Slant Focal Length (SLF) to an accuracy of 0.3%.