From the two aspects of external environmental factors and vehicle factors, this paper studies the influence of in-car temperature, humidity, vehicle type, vehicle mileage, vehicle exhaust displacement and other factors on the harmful volatile organic compounds (VOC) in the automobiles. The research results show that: in terms of external environmental factors, the increase of temperature and relative humidity in the car will cause the in-car VOC concentration to increase, and the temperature has a more significant influence on the VOC concentration in the car; being in area with poor environment and serious exhaust emissions for a long time will increase the VOC concentration in the car; when the natural wind speed increases, the concentration of VOC pollutants in the car gradually decreases. In terms of vehicle factors, the VOC concentration in high-end cars is significantly higher than that in low-end cars, and the VOC concentration of new cars is higher than that of old cars. As the car age and mileage increase, the VOC concentration in the car begins to decrease. The vehicle exhaust displacement is proportional to the VOC concentration in the vehicle, and the interior space is inversely proportional to the VOC concentration. The influence of the change in the interior space on the harmful VOC concentration is relatively small.