Abstract: In order to reveal the mechanism of nitrogen release of polymer-coated fertilizers, the N release characteristic from 4 polymer-coated fertilizers which have different produce technics and nutrition release mechanism was investigated in this paper. The results showed that: based on the experiments of nitrogen release under different vapor pressure, the cumulate release rate of nitrogen from polymer-coated fertilizers was: H2O＞saturated solution of KH2PO4＞saturated solution of KCl; the nitrogen release activation energy from polymer-coated fertilizers was: H2O＜saturated solution of KH2PO4＜saturated solution of KCl. The cumulate release rate of nitrogen from polymer-coated fertilizers increased as the difference between vapor pressure in or out integument increasing, and both the coated materials and the types of nutrient affected the release rate of nitrogen release from fertilizers.