The present invention discloses a vehicle-inside noise indoor testing device and a testing method thereof. Through the arrangement of a closed testing cavity and through the use of a spring support to connect a testing tire, the device provides a way to separately study the noise in the vehicle caused by the road surface excitation, and is absent from the interference with the testing results from engine vibration, ambient noise and other external disturbances; and then, the testing tire is raised to a certain height and released to achieve impact of the road surface on the vehicle wheel and the excitation under the condition of vehicle driving. This reduces the length and workload required for the paving of an indoor road surface testing piece. The manner featuring the arrangement of the closed testing cavity and the collection of the vehicle-inside noise meets the transmission mode of the vehicle-inside noise caused by the road surface excitation. According to the invention, based on the research on the relationships of the vehicle-inside noise and the road surface paving structure and the surface texture characteristics, the main factors including the vehicle-inside noise can be determined. The device of the invention can be manufactured at a low cost, occupies small space and does not have to be paved with corresponding road surface. In addition, the testing is convenient and the result reappearance is also good.