The SeDeM expert system is used to reveal direct compression (DC) suitability of the active ingredients and excipients in preformulation. In this study, the system was used to predict compressibility of rhodiola extract (RhE) and its mixture with excipients. The parameter index (IP), parameter profile index (IPP), and good compressibility index (IGC) of RhE mixtures with different fillers were investigated. The results showed that RhE and mixture with lactose or starch were not suitable for DC according to the values of IP, IPP, and IGC, which can be corrected by pregelatinized starch (P-STA). The quality of tablets corrected by P-STA all satisfied the USP monograph limit. The findings from this study showed that the system is a useful tool to predict DC suitability on the mixture of RhE and an excipient.