Superparamagnetic polymers (SPMP) microbead was an excellent form for nanosized magnetic particles less than 10nm to realize their potential applications in many fields. We developed a novel modified suspension polymerization method for the production of superparamagnetic poly ( methacrylate divinylbenzene) ( PMA-DVB) microbeads, with amino groups on their surface after simple modifications. We applied these SPMP microbeads to establish a sandwich enzyme chemiluminence immuno (ECLIA) procedure of detecting the free hCG beta in serum. It was proved to a better method compared to the ELISA, since it need half of the sample volume, simpler protocols, and the time it need was shortened from 2 hours to 1 hour. The detection limit was 0.22 mIU.m(-1), one order lower than the ELISA assay. Its linear range was between 0.45 - 185.2 mIU.m(-1). And in the detections of clinical serum samples, the related coefficient between the two methods' results was 0.955.