The end-face reflection property of micro-nano fiber (MNF) is one of its important transmission features, which plays remarkable roles in a variety of practical applications of MNF. In this paper, we propose a novel method to study the MNF end-face reflection property using an optical circulator, which overcomes the deficiencies of the direct measurement relying on a 3 dB coupler. On the basis of this method, we further introduce the aerogel fixing and power compensation techniques to effectively eliminate ...