[Objective]To research on the detection method of trace Cd content in RADIX REHMANNIAE,and to provide method for the quality control of traditional Chinese medicines.[Methods]1-(-2-pyridylazo)-2-naphthol was taken as the complexing agent.Cloud point extraction-flame atomic absorption spectrometry was used to detect the trace Cd content in RADIX REHMANNIAE with Triton X-100 as the surfactant.[Results]The optimal test condition was as follows:1.5 mL monopotassium phosphate-dipotassium phosphate buffer(pH 8.0),0.5 mL of 4.0×10-4mol/L PAN ethanol solution,0.1 mL of 1%(V∶V)Triton X-100,70℃heating temperature,20 min heating time,15 min centrifugation time and 5 min ice water bath.The detection wavelength was 240.7 nm;spectral passband was 0.4 nm;work lamp current was 2.0 mA;preheating lamp current was 2.0 mA;propane flow was 1 700 mL/min;and negative voltage was 300 V.Under this condition,the linear regression equation of Cd was y=0.212 1x-0.001 2,R=0.999 5;the detection limit was 0.090μg/L(n=11),RSD was1.61%;and recovery rate was 97.50%.The Cd content detected in RADIX REHMANNIAE was 1.025μg/g.[Conclusions]This method was sensitive and simple,and could be used to detect the trace Cd content in RADIX REHMANNIAE.And the results were satisfactory.