Some radiometric and photometric measurements need high accuracy knowledge of the area of the aperture. So the accurate knowledge of the area of the limiting aperture is very important. There are two types of methods to measure the aperture areas. Type-one contains contract method, and no-contract method, and type-two contains geometrical method and effective area method. In this paper we first describe all the methods briefly, then emphatically explain the no-contract method, geometrical method and effective area method. Finally, a comparison of measurement accuracy, degree of difficulty in measurement, and equipment cost among different methods, indicates that the geometric method and the effective area method are very promising. In order to improve the uncertainty of the measurement, more stable laser and accurate translation stage are needed.