Objective: High performance liquid chromatog.(HPLC) was established for determinationof related substances in dexlansoprazole for injection.Methods: The Agilent Extend-C18(250 mm x 4. 6 mm, 5 μm)was used, with triethylamine-water( pH adjusted to 6. 2 with phosphoric acid)-acetonitrile(1 : 60 : 40) as themobile phase at the detection wavelength 285 nm, with flow rate of 1. 2 mL/min.The methods of related substancesinspection were studied specifically, and the methods of linearity, precision, solution stability and recovery ofknown impurities were investigated.Results:Each impurity peak could be well separated from the main peak, therewas no chromatog. peak of blank excipient solution appeared after 3 min of retention time;the limit of detectionof impurities A ∼ E control was 0. 017, 0. 016, 0. 019, 0. 023 and 0. 009 g/mL resp.; the limit of detectionof impurities A ∼ E control was 0. 006, 0. 005, 0. 006, 0. 008 and 0. 003 g/mL resp.; the average recovery ofimpurities A ∼ E at 3 concentrations was 97. 7%, 98. 2%, 100. 4%, 102. 4% and 97. 0% resp., within97. 0% ∼ 103. 0%, and the RSD was 2. 8%, 2. 0%, 2. 5%, 2. 1% and 3. 0% resp.Therewas good linearrelationship between the peak areayand the concentrationxfor impurity A within 0. 017 ∼ 3. 27 μg/mL, impurity Bwithin 0. 016 ∼12. 97 μg/mL, impurity C within 0. 019 ∼ 4. 09 μg/mL, impurity D within 0. 023 ∼ 4. 40 μg/mL andimpurity E within 0. 009 ∼ 3. 20 μg/mL.Conclusion: This method is highly specific, and the auxiliary materialsdoesn't interfere with the determination of related substances.It is sensitive, simple, reliable, accurate and reproducible, which is suitable for the determination of related substances in dextrolansoprazole for injection.