With Al2O3 and SiO2 as polishing medium, under different polishing conditions, e.g. with different polishing pressure, polishing time and polishing fluid, the influences of polishing treatment on the return loss of optical fiber connectors were investigated. The return loss of optical fiber connectors is 32 - 38 dB before polishing. The results show that dry polishing(i. e. no polishing fluid) with Al2O3 has less influence on return loss of optical fiber connectors, while dry polishing with SiO2 reduces return loss to about 20 dB because of the end-face of optical fiber contaminated. The wet polishing(i. e. using distilled water as polishing fluid) with Al2O3 or SiO2 can increase return loss to 45 -50 dB, but wet polishing with Al2 O3 may produce optical fiber undercut depth of 80 - 140 nm. Wet polishing with SiO2 should be preferentially selected for optical fiber connectors and polishing time should be controlled within 20 - 30 s.