The invention discloses a testing apparatus of a high-pressure water mist system. The testing apparatus comprises a high-pressure water mist pump set, the high-pressure water mist pump set is connected with the high-pressure water mist system, the water outlet end of the high-pressure water mist pump set communicates with a water inlet side high-pressure ball valve in a valve box through a water inlet pipe, the water inlet side high-pressure ball valve sequentially communicates with a high-pressure electric ball valve and a water outlet side high-pressure ball valve, the water outlet side high-pressure ball valve is connected with a test high-pressure water mist spraying head for testing through a water outlet pipe, a control box is arranged in the valve box, and the high-pressure electricball valve is in circuit connection into the control box. The running condition of the high-pressure water mist system can be tested at any time conveniently, the fireproof risk caused by equipment failures can be reduced, stability and application of the high-pressure water mist system can be improved, an operation department can conveniently repair or replace equipment accessories in time, andit is ensured that the high-pressure water mist system can be normally started under the fire condition.