A device for testing performance of photocatalytic ozonation in degradation of volatile organic compounds. The device includes an air generator, an oxygen cylinder, a volatile organic compound cylinder, a mass flow meter, an ozone generator, a humidifier, a thermohygrometer, a gas mixer, a light source, a plate-type reactor, an ozone analyzer, a gas chromatographic instrument, a first valve, a second valve, a third valve and a tail gas treatment unit; The experimental device of the present invention is suitable for the experiment of photocatalytic degradation of volatile organic gases in mixed gas, and has the advantages of wide experimental conditions, simple structure, convenient use, reliable performance, etc.