In order to reduce volatile organic compounds (VOCs) in a vehicle and find the solution, this study proposes a new mathematical model and method of quantitative analyzing and tracing VOCs at multi-levels. In the present work, it is the first time to establish a multi-level VOCs mathematical analysis model and tracing method from vehicle parts to a whole vehicle by synthetically considering both the interactive effects of VOCs compositions emitted from different vehicle parts, and the hazard level of each composition of VOCs based on the national standard limits. This study also applies the multi-objective decision method with the triangular fuzzy number semantics definition theory to construct a pairwise comparison matrix for quantitatively analyzing the influence weights of different levels and the combined weights of multi-levels. The proposed VOCs tracing method can not only accurately analyze the contribution sequence of different VOCs compositions to the VOCs in a whole vehicle, but also quantitatively calculate the contribution of each typical vehicle part to the VOCs in a whole vehicle considering the interaction effects of different VOC compositions coming from different parts, and thus providing a more accurate theoretical method for the traceability and control of VOCs in vehicles. The case study shows that the contribution sequence of different VOC compositions is ranked as formaldehyde > acetaldehyde > toluene > xylene > ethylbenzene. The contribution sequence of vehicle parts to the VOCs in a whole vehicle is ranked as front seats > rear seats > carpet > dashboard and ceiling. The case study proves that the contribution of a vehicle part to the VOCs in a whole vehicle is not a simple superposition of all VOCs compositions, and it is the interaction results coming from different vehicle parts.