Abstract: Menthae Haplocalycis herba, one kind of Chinese edible herbs, has been widely adopted for the clinical use in China for thousands of years. Over the last decades, the studies on chemical constituents of Menthae Haplocalycis herba have been widely reported. However, too much attention had been paid for its volatile constituents. Non-volatile components are also responsible for its medical efficacy based on the fact that it is usually decocted with water in the clinical practice. In the present study, a method of ultra-high performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry (UHPLC-LTQ-Orbitrap HRMS) was developed for a comprehensive study of the chemical constituents in Menthae Haplocalycis herba aqueous extracts. Separation was performed with an Acquity UPLC^® BEH C18 column (2.1 mm×100 mm×1.7 μm) with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase with the speed of 0.30 mL/min under gradient conditions. Based on the accurate mass measurement (error<5×10^-6), MS/MS fragmentation pathways, different chromatographic behaviors, an important parameter ClogP value and compared with the standards and references, 85 compounds were unambiguously identified or tentatively characterized, including 38 flavonoids, 16 phenolic acids, 24 terpenoids and 7 phenylpropanoids. The result demonstrated that UHPLC-LTQ-Orbitrap HRMS can improve the analysis efficiency of the chemical constituents of traditional Chinese medicine (TCM) extracts, which also benefit to lay the chemical foundation for rational development of medical and edible value of Menthae Haplocalycis herba.