Abstract: In this paper, "drop test" has been adopted to test tyres with its simple equipment requirement, easy manipulation and reliable tested result. For verifying the test precision, the compute simulation of the test system has" been conducted. It is proved that this test system can be simplified as a 3 degrce-of one freedom damped free vibration model which is used to rectify the mistake in calculation of dynamic parameters of tyres or to direct the improvement of test equipment.