Objective: To optimize extraction conditions of total nucleosides in Codonopsis tangshen. Method: Ultrasonic method was adopted to extracting total nucleosides in C. tangshen. Taking the contents of total nucleosides (cytidine

uridine

guanosine and adenosine) as index

based on single factor tests

orthogonal test was designed to optimize extraction conditions of total nucleosides in C. tangshen. HPLC was employed to determine the contents of cytidine

uridine

guanosine and adenosine with mobile phase of methanol-water for gradient elution and detection wavelength at 260 nm. Result: The influence of various factors on the extraction rate of total nucleosides was on order of volume fraction of methanol > extraction times > solid-liquid ratio > extraction time. Optimal parameters was as follows:extracted twice with 10 times the amount of water for 30 min of each time. Under these conditions

extracting amount of total nucleosides was 1.523 mg·g-1. Conclusion: This established HPLC method is accurate and reliable to detect contents of total nucleosides. At the same time

this optimized extraction technology is stable and feasible with the advantages of energy-saving

rapidity

efficient and so on.