Using recombinant human calmodulin(rhCaM), cyclophilin(rhCyP), cardiolipin and double strained DNA (dsDNA) as coating antigens, an indirect enzyme immunoassay (EIA) for autoantibodies against 4 antigens was developed. and investgated the pre- and post UV-irradiation of polystyrene (PS) microtitre plateas solid phase. It was found that, compared with non-treated PS, the irradiated PS plate could significantly improve the performance of assay result, and its detective sensitivity as well as reproducibility of 4 autoantibodies were significantly elevated. Surface characterizations were done by AFM, and AFM photo-pictures furnished the powerful direct evidence of improving EIA. Antigens were well-distributed on the surface of UV-irradiated PS, whereas non-treated samples shown not uniform, the percent of moleculars which adsorbed was very low and accumulative. XPS analysis revealed the bottom of the wells which irradiated were oxidated, and induced peroxide reactive groups. The ratio of oxygen and carbon (O/C) was 6.9-fold higher than that of non-treated PS, and increased the surface hydrophylicity as well as chemical reactivity. This is the main reason for improved performance of UV-irradiated EIA plates.