Wood and paper materials are the main sources of organic acids in the air of museums. Released volatile organic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid and other short-chain organic acids. These organic acid gases will lead to the corrosion of bronze relics, surface weathering of lead utensils, corrosion and embrittlement of enamel and pottery, deterioration of silk fibers, and shortening of paper life. In our study, a method based on ion chromatography for the simultaneous determination of formic acid, acetic acid, propionic acid, butyric acid and valeric acid in the air of museum was established. Using ultrapure water as an absorbent with the volume of 10 mL, air samples were collected by the active sampling method at a flow rate of 400 mL/min. A 5 mmol/L KOH eluent was used for isocratic elution, and concentrations of the five volatile organic acids could be determined simultaneously within 9 min. The results show that in the linear range of 0.05~0.5 μg/mL, correlation coefficients of formate, acetate, propionate, butyrate and valerate were higher than 0.995, detection limits were 0.001~0.009 μg/mL and quantitation limits were 0.004~0.030 μg/mL. Recoveries of the five organic acids were 91.4%~107.4%. Concentration ranges of formic acid and acetic acid detected in Warehouse A were 36.40~85.44 μg/m³ and 274.42~312.11 μg/m³, respectively, and concentration ranges of formic acid, acetic acid and propionic acid detected in Warehouse B were 18.66~34.00 μg/m³,123.53~152.55 μg/m³ and 15.80~24.48 μg/m³, respectively. This method has the advantages of simple sampling, no sample pretreatment, short detection time and low cost, which is suitable for the daily detection in museums.