The processing of toxic ethnomedicines is of great significance for their safe clinical application. Thus, the limitations of traditional processing should be addressed, and the processing method of ethnomedicines should be standardized using modern research methods. In this study, the processing technology of a commonly used Tibetan medicine Tiebangchui (TBC), the dried root of Aconitum pendulum Busch, processed with highland barley wine was optimized. Diester-diterpenoid alkaloid (DDA) (aconitine, 3-deoxyaconitine, 3-acetylaconitine) and monoester-diterpenoid alkaloid (MDA) (benzoylaconine) content were used as evaluation indicators, and the weight coefficient of each evaluation index was determined by the entropy method. The single factor test and Box-Behnken design were used in investigating the influence of the ratio between highland barley wine and TBC, slice thickness of TBC, and processing time. Comprehensive scoring was performed according to the objective weight of each index determined by the entropy method. The optimal processing conditions of TBC with highland barley wine were as follows: the amount of highland barley wine is five times that of TBC, a soaking time of 24 h, and a TBC thickness of 1.5 cm. The results showed that the relative standard deviation between the verification test and predicted value was less than 2.55% and the optimized processing technology of TBC processed with highland barley wine is simple, feasible, and stable, and so can provide a reference for industrial production.