Straw fiber wall structure is a new structural system with properties of lightweight and energy-saving, heat preservation and sound isolation. Firstly, the impact of chemical component, structure on basic thermal performance such as activation energy, heat productivity, heat release rate was studied in details. Secondly, the chemicophysics reaction in high temperature were studied through TG-FTIR experiment. Finally, the linear stepwise regression model about fire temperature and loss on ignition was established based on loss on ignition experiment and DRS2.6 software analysis system. Furthermore, a 200mm thickness straw fiber external thermal insulation plate was chosen and burned in independent designed ISO9705 standard fire test room in order to verify the accuracy of the regression model. The results show that the model is correct and can be applied to the real engineering computation and assessment.