Objective A HPLC method was established to measure the contents of major nucleosides in Hyriopsis cumingii.Method Separation was performed on a Lichrosper-C_(18) column, pure water was used as mobile phase,the flow rate was 1.0mL min~(-1),the column temperature at 30℃and the detective walvelength at 254 nm.Results The contents of uracil,hypoxanthine, xanthine,uridine and thymine were 153.2～173.3?g?g~(-1),106.6～360.8?g?g~(-1),117.6～172.8?g?g~(-1),70.3～153.1?g?g~(-1) and 343.9～511.4?g?g~(-1),respectively. Conclusion This method showed good repeatability and flexibility.It could be used as a conventional method for determination of major nucleosides in H.cumingii.