采用红外光谱技术研究了聚氨酯砂的固化反应机理， 通过向聚氨酯砂中加入呋喃树脂砂进行改性处理， 并采用热失重及扫描电子显微分析技术研究了聚氨酯砂的改性机理。结果表明， 聚氨酯砂中加入呋喃树脂砂以后， 由于在高温下树脂膜分解速度下降， 高温强度得到提高。呋喃树脂砂合适加入量为１０ ％ ， 改性聚氨酯砂具有良好的综合性能 The curing reaction mechanism of polyurethane sand was studied by infrared spectroscopy. The modified sand was treated by adding furan resin sand to the polyurethane sand. The modification mechanism of polyurethane sand was studied by thermogravimetry and scanning electron microscopy. The results show that after adding furan resin sand to polyurethane sand, the high temperature strength is improved due to the decrease of resin film decomposition rate at high temperature. Furan resin sand suitable amount of 10%, modified polyurethane sand has a good overall performance