Utilizing polarizing beam splitter (PBS) and polarizing beam combiner (PBC), a dual-loop optoelectronic oscillator (OEO) is designed without adding any active device. This oscillator can simultaneously produce optical and electrical output. No additional electronic noise can be introduced because of avoiding additional active devices. Furthermore, there is no signal frequency fluctuation and beat noise caused by interference and beating due to optical carrier orthogonally coupled in optical domain. According to the analysis of optoelectronic oscillator, dual-loop is able to effectively suppress the side modes in each single loop. Through experimental comparison, the side mode suppression ratio is improved by 30～70 dB. Finally, we demonstrate the free-running experimental result, which has high quality spectrum at 12 GHz with side mode suppression ratio 50～70 dB, phase noise of -93 dBc/Hz at 10 kHz from carrier and Q value of 1010.