Memory declined and cognitive impairment are common complaints in neurology clinics. Before diagnosing as dementia, individuals will undergo a transition period, including mild cognitive impairment (MCI). Neuroinflammation is an important mechanism of memory problems. For patients with MCI, there are limited available medications. Currently, there is no standardized treatment in Taiwan. The purpose of this study is to explore alternative treatment with essential oil by inhalation to improve memory, sleep, mood, and quality of life for patients with MCI. This study will include patients who are clinically diagnosed as MCI by a neurologist. This is a double-blind randomized controlled trial, which will include 100 participants with 1:1 allocation into the intervention group and control group. The experimental group will receive 100% CXMCI-01-M Essential Oil every morning and 100% CXMCI-01-N Essential Oil by inhalation every night. The control group will receive 0.1% CXMCI-01-M Essential Oil every morning and 0.1% CXMCI-01-N Essential Oil by inhalation every night. The intervention method involves inhaling for 5 minutes, followed by wearing an essential oil necklace for 60 minutes. Examinations will be conducted before intervention (first visit, V1) and 28 days later (second visit, V2). After 28 days of finishing intervention, the third visit (V3) will be conducted. The primary outcome is the Contextual Memory Test (CMT). Secondary outcomes are Montreal Cognitive Assessment (MoCA), Taiwan Odd-Even Number Sequencing Test (TOENST), Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Pittsburgh Sleep Quality Index (PSQI), and 36-Item Short Form Health Survey (SF-36). Serum biomarkers of amyloid, tau protein, and metabolomics will be checked, as well as urine biomarkers related to neuroinflammation, including lipid peroxidation (LPO), 8-hydroxy-2-deoxyguanosine (8-OHdG), kynurenine, picolinate, quinolinate, and kynurenate. Changes in meridian energy will also be examined by M.E.A.D. and HRV before and after the intervention. It is expected that this study will contribute to the clinical application of CXMCI-01 Essential Oil in patients with MCI and improve their memory, mood, and sleep quality.