The partition coefficients K-paper/air of DBP and benzophenone between three kinds of paper cups and air were studied using microsamping. The results showed that K-paper/air decreases with temperature increasing. At 70 ℃, the range of K-paper/air of DBP and benzophenone is 105.723~1638.894 and 67.469~991.849 respectively; while at 100 ℃, the range is 28.661~360.978 and 7.506~407.225. K-paper/air value is not only related to the boiling point of the compound, but also to the thickness, ration and tightness of paper cup. K-paper/air increases with thickness, ration and tightness increasing, and this leads to lower migration of DBP in paper cups.