A new approach based on the model-free method was proposed to deduce the most probable mechanism function.Firstly

the kinetic models were screened in accordance with the reaction process.Secondly

the Popescu method was adopted to do further screening by virtue of linear correlation coefficient of regression calculation.Finally

the apparent activation energy that was obtained by a combination of the differential method based on single-heating rate and the equi-conversion method based on the multiple-heating rate methods was used to confirm the most probable mechanism function.This approach could avoid the kinetic compensation effect

and in the course of calculation almost no hypothesis or approximation was made and the error caused by differential calculus could be reduced on account of the multiple-heating rate method.The mechanism functions could be easily distinguished when the apparent activation energy other than the linear correlation coefficient was served as the criterion.Thermogravimetry was used to analyze the decomposition of three kinds of limestone，and the result indicated that the shrinking cylinder mechanism with controlling surface reaction rate was the most probable kinetic function.