Objective To select omeprazole content changes smaller with dispensing method and to seek for rationality of off-label uses.Methods To measure content change of omeprazole sodium for injection mixed by different subscriptions at different time through HPLC, and compared effect of different dispensing methods on content of omeprazole sodium for injection.Results 10 mL 0.9%sodium chloride injection was chosed as dissolvent,the change of omeprazole sodium for injection content would be minor, and stability of drug solution was superior.Conclusion Dispensing methods of drug impact on its'security and validity, which is part of discuss category about medicine rational use as well.Off-label uses could not vest in unreasonable use, which should contingent on specific document,data and actual environment of medical treatment.