Background: Alismatis Rhizoma (AR) is a traditional Chinese medicine that is frequently used for the treatment of hyperlipidemia, hypertension, diabetes, and chronic kidney failure. Active alisols contribute to the beneficial effects of AR and AR products. Objective: In the present study, we investigated the stabilities and transformations of alisol B 23-acetate (B23), alisol A 24-acetate (A24), alisol A (AA), and alisol B (AB) in AR and proprietary traditional Chinese medicine prescriptions. Materials and Methods: We first established an ultra-high performance liquid chromatography/triple quadrupole mass spectrometry method for the analysis of AR products. Next, extracts and concentrates of AR and the proprietary prescriptions were prepared and heated at different temperatures. Finally, the developed method was applied to the analysis of these samples. Results: Our method is sensitive, precise, accurate, and reliable for the analysis of these four compounds. The extraction efficacies of the alisols from decoctions prepared from single herb and from mixtures of herbs showed large differences (P < 0.01). The alisols are highly sensitive to changes in temperature and pH and transform during heating. B23 can be transformed to AA and A24, and AB can be transformed to AA. Conclusion: These results indicate that the content change of aliols may affect the quality and efficacy of AR and AR products. Therefore, temperature and pH should be controlled during the manufacture of AR and AR products.