A novel chemiluminescent(CL) aptasensor for ochratoxin A(OTA) with magnetic beads as separate carrier was designed.Firstly,the capture DNA and OTA aptamer were immobilized on the surface of the magnetic beads,then the biotin-reporter DNA and OTA were taken to competitively bind to the OTA aptamer.Finally,streptavidin-gold nanoparticles(SA-AuNPs) and NH2OH/Au3+ were added sequencely in order to improve the sensitivity for CL detection on OTA.The effects on the experiment including magnetic beads，capture DNA，aptamers，biotin-reporter DNA and dilution multiple of SA-AuNPs,were optimized.Under the optimized experimental conditions,there existed a good linear relationship between the CL intensity(ΔCL) and the logarithms of OTA concentration(r2=0.992 5) in the range of 0.01-50 ng/mL,with a detection limit of 1.58×10-3 ng/mL.In the recovery experiments by adding different concentrations of OTA to the beer samples,the recoveries ranged from 97.4% to 105.4% with the relative standard deviations of 4.0%-5.5%.