Abstract: This paper discussed the hot reaction characters of glue in wheat straw board(methane diisocyanate (MDI)、urea formaldehyde (UF), and improved UF )and the relationship between them by DSC. The result shows that the hot reaction of MDI is steady and there is neither decalescence nor give out hot in the area of the tested temperature. When MDI and water are heated together, there are reactions of decalescence and give out hot . Compared the UF with improved UF in this research, both hot reaction characters are evidently different. The decalescence reaction improved UF is ahead and its total amounts of decalescence are reduced.