The quantitative nuclear magnetic resonance spectroscopy(qNMR)method for the determination of icariin in Ruzengning capsule was established based on solid phase extraction(SPE).The sample powder in capsule was ultrasonically extracted using 10%alcohol as solvent at room temperature.The extraction solution was enriched and cleaned with an HC-C18 SPE cartridge.The effects of ultrasonic extraction and SPE,qNMR experimental conditions were investigated.The qNMR experiment conditions were selected as follows：using deuterated DMSO as solvent,2,3,5-triiodobenzoate as internal standard,a P1(pulse width)of 14.1 μs,and a NS(number of scan)of 256.The 1H NMR peak of δ 7.9(2,6-H,d,2H)of icariin was chosen as the quantitative peak.Method validation was performed with the intra-day RSD of 0.43%and the inter-day RSD of 0.75%.The linear correlation coefficient(r)was 0.999 9 between the peak area ratio and mass ratio of icariin to internal standard.LOD was 0.122 mg/g and LOQ was 0.368 mg/g.The recoveries of the SPE-qNMR were in the range of 99.8%-103.0%.The result showed that the method was stable,accurate and reliabile.With no need of icariin standard,the method was applied in the determination of icariin in 3 batches of real Ruzengning capsule.