The invention relates to a trimethylglyine compound nanoemulsion used for nourishing and moisturizing skin and a preparation method thereof. The nanoemulsion is prepared from the following raw materials in parts by weight: 10-17 parts of isopropyl myristate, 20-25 parts of Caprylocaproyl Macrogolglycerides, 6-16 parts of polyglyceryl fatty acid ester, 33-38 parts of triple distilled water, 0.1-1.0part of citric acid, 5.5-12 parts of Trisodium citrate dihydrate, 13-19 parts of trimethylglyine lactone, 13-19 parts of hydroxyethyl carbomite, 36-46 parts of Vitamin E and 10-16 parts of azone. Theinvention has the innovations that the newest international drug targeting vector transfer system is improved and optimized so as to enable the nanoemulsion to have dual effects of nourishing and moisturizing skin; the nanoemulsion can be made up and produced only at normal temperature, and the complex processes of respectively dissolving, heating, then mixing and emulsifying the oil phase and the water phase are not needed; the process is scientific, the operation is simple, special equipment is not needed, the preparation period is short (about 30 min), the production efficiency is high, and the industrialization is easy to realize; moreover, the nanoemulsion has stable quality, high comfort and high safety, and the effect ingredients are not easy to break; compared with the like products, the nanoemulsion has better effect, saves more energy, energy resources, materials, time and cost, reduces environmental pollution and the like.