In this paper, the idling and low speed booming problem of a car is analysed and solved by means of experiment and fi- nite element simulation technology. The idling and low speed booming is caused by the first order longitudinal bounce and low frequency mode of the trunk. The structure of the trunk is optimized to solve the idling and low speed booming at the same time, using 1DCAE con- cept to simplify the problem to the single-degree-of-freedom system, and the countermeasures are verified on the real car, both the sub- jective evaluation and objective test results show that idle and low speed booming have been significantly improved to achieve the target level. It offers some guiding to the automotive NVH performance development.