We have developed a lateral flow assay (LFA) for the detection of bisphenol A (BPA) in water samples. Antibody against BPA was labeled with gold nanoparticles, and these conjugates were used as the recognition probes for the construction of an LFA strip. The diameter of the gold nanoparticles, the amount of antibody, the pH of the buffer, and the categories of the conjugation pad were optimized. The resulting method has a (visual) detection limit of 5 ppb, and of 0.92 ppb if used in combination with professional software. This LFA displays excellent specificity and was applied to spiked water samples with satisfactory results.