Abstract: Processing accuracy is one of the important quality indicators of wheat flour. In order to explore the feasibility of evaluating the processing accuracy of wheat flour by thermogravimetric method, the pyrolysis behavior of 35 kinds of on-line flour flow from different milling systems was measured by thermogravimetric analyzer. The kinetic parameters of on-line flour flow in stage Ⅱ (238-338 ℃) of thermal decomposition, including activation energy, pre-exponential factor, and reaction order, were obtained based on the thermal decomposition kinetics equation. The correlation between activation energy and bran content in on-line flour flow pyrolysis stage Ⅱ, residual mass fraction and ash content after online flour flow pyrolysis stage Ⅲ was established by regression analysis. There was a nonlinear negative correlation between the activation energy of pyrolysis stage Ⅱ and the content of bran star (R²=0.920 1). There was a linear positive correlation between the residual mass fraction of on-line flour flow after stage Ⅲ of thermal decomposition and the ash content in different milling systems, with the highest correlation coefficient R² being 0.920 7. Bran content is one of the main factors affecting the pyrolysis characteristics of on-line flour flow. Thermogravimetric analysis method is suitable for evaluating the processing accuracy of wheat flour with high bran content.