In the development, production and maintenance of polarization-maintaining sensing systems, high-speed electro-optical modulation systems and passive optical devices, the requirement for the polarization extinction ratio is gradually increasing. For this purpose, a measuring technology of polarization extinction ratio with high speed and wide dynamic range is proposed. First, the basic principle of the rotation analysis method is described, then the power detection method of the logarithmic amplifier used in this technology is introduced, and finally the test results of the ordinary polarization extinction ratio tester and the improved polarization extinction ratio tester are compared. The results show that the new measuring technology of polarization extinction ratio improves the speed and dynamic range of the extinction ratio test, solves the problems of the current measuring technology, and therefore meets the relevant needs in the market.