Objective: In order to further improve the reliability and scientificity of tobacco usability evaluation results in threshing and re-drying process, and to enhance the value of tobacco purchased by cigarette enterprises. Methods: An optimal combination weighting method based on moment estimation theory was proposed to evaluate the availability of chemical components in tobacco leaves. First, based on the subjective and objective weights, with the objective of minimizing the deviation between the combined weights and the subjective weight, the relative importance coefficient of the subjective weights and objective weight was solved to determine the optimal combined weights of chemical indexes. Second, combined with the membership function, the chemical composition index of the tobacco leaves was used as the data set to calculate the availability value of the chemical composition of the tobacco leaves. Furthermore, the usability of tobacco leaves during threshing and re-drying process was evaluated. Finally, the finished tobacco leaves from the Qilin re-drying plant was taking as the object of analysis. Results: This method can fully consider subjective and objective factors, making the weighting results and evaluation results more consistent with the actual situation. Conclusion: The combination of weighting by moment estimation theory can make a more reasonable and scientific evaluation of tobacco leaf usability during threshing and redrying process.