Abstract:[Objective] Based on immunoassay, we developed a method to detect Potato Virus A (PVA) using one-step cytometric bead array (CBA). [Methods] Using fluorescent beads as carriers, we formed the complexes of bead-capture an-tibody-PVA-fluoresceinisothiocyanate (FITC) labeled detection antibody by immunoreaction of double antibody sandwich on bead surface. We measured the fluorescent signals produced from beads and from FITC with a multiparameter flow cytometer. [Results] By optimization test, capture antibody and detection antibody (from PVA detection kit, Agdia, USA) were finally diluted at 1:50 (4ug/mL) and 1:25 to be used in one step CBA, respectively. A total CBA reaction time of 2 h was needed. No cross reactivity with other plant virus similar to potato virus Y, lettuce mosaic virus and tomato ring spot virus were found. Detection sensitivity for positive control sample in one-step CBA was 4 folds higher than that in normal plate double antibodies sandwich enzyme-linked immunosorbent assay (DAS-ELISA). [Conclusion] A one-step CBA method for rapid and sensitive detection of PVA is developed.