A high accuracy method of qNMR with inverse gated decoupling technique was established to determine the content of phenylethanolamine A.Considering the choice of deuterated solvents,internal standards and quantitative peaks,and the optimization of relaxation delay,aquisition number and temperature,the final measurement conditions of qNMR spectra were as follows:flip angle:30°,date point:32 K,detection temperature:293 K,a relaxation delay:33.64 s,acquisition times:64 times,line broadening:0.3 Hz.The experimental results showed that the stability of this condition could be maintained for 24 h.A good linear relationship was obtained between peak area ratio and molar ratio in the range of 0.333-3.333,and the correlation coefficient (r2) was 0.999 9.The established method is specific,accurate and simple,and could be used for the content determination of this kind of compounds.