6 as solvent, entecavir as a sample, and 1,4-dinitrobenzene as an internal standard, the 1H-NMR data of entecavir were characterized, calculate the assay of entecavir by comparing the response signal area of sample (As) and internal standard (Ar). Results One sample solution was determined under the same NMR conditions for six times, the RSD value of As/Ar was 1.1%; When prepared and characterized three samples, the content of entecavir calculated was 93.8%, RSD was 0.70%. The results were consistent with that using mass balance method (93.8%). Conclusion Using qNMR to characterize the assay of entecavir can avoid the use of reference substance. This is a precise, rapid, and effective method to characterize the contents of chemical samples."/>