Abstract: The solution behavior of omeprazole was studied by ¹H NMR and ¹³C NMR. It was confirmed that there was tautomerism of azaaryl ring in the solution. The tautomerism of azaaryl ring had an obvious effect on the NMR results, leading to peak shifts and signal strength. The quality of the NMR spectra was improved by adjusting the solvents (chloroform, methanol, dimethyl sulfoxide), temperatures (room temperature and 80 ℃) and amounts of alkali. By adding alkali to break the hydrogen bond, the hydrogen atom and carbon atom in the molecular structure have corresponding enhanced signals in ¹H NMR and ¹³C NMR spectrum, which is conducive to the analysis of compounds.