Recently, increasing attention had been paid for using peracetic acid (PAA) as an efficient disinfectant or a strong oxidant in wastewater treatment. In this study, a rapid and simple spectrophotometric method for the selective determination of PAA in aqueous solution was established, based on the oxidative decolorization of rhodamine B (RhB) by reactive species generated from the combination of PAA and Co(II). Under the optimized conditions (20 μmol L-1 RhB, 1.0 mmol L-1 Co(II), pH = 5.0 buffered with 10 mM acetate acid buffer, and reaction time = 40 s), the extent of RhB decolorization at the characteristic wavelength of 552 nm was found to be proportional to the concentration of PAA in the aqueous solution. A strong linear correlation was observed between the consumption of RhB and the concentration of PAA in the range of 0.25-25 μmol L-1 (R2 = 0.9991), and the sensitivity for PAA was as high as 2.99 × 104 M-1 cm-1. The RhB spectrophotometric method is effectively tolerant to interference the coexistent H2O2 in PAA solution, the common coexisting species in practical water samples (KCl, MgSO4, NaNO3, NaHCO3, DCF and humic acid) and even the added reducing substances such as hydroxylamine and ascorbic acid. As a selective colorimetric agent, RhB is resistant to interference from reducing substances and water bodies, enabling accurate determination of PAA concentration in actual water environments. Overall, the RhB spectrophotometric method could be used as an alternative method for the cheap, rapid and selective determination of PAA in water samples.