Abstract: OBJECTIVE To establish a method for determination of rhaponiticin illegally added in Fuyanxiao capsules. METHODS TLC and HPLC were employed to isolate and analyze the extract from Fuyanxiao capsules suspected of illegal composition of rhaponiticin, and rhaponiticin was identified by HPLC-DAD. RESULTS Fuyanxiao capsules were detected to contain illegal composition of rhaponiticin. CONCLUSION The established method is specific, sensitive and convenient. It can be used efficiently for control and surveillance of illegal composition of rhaponiticin in Fuyanxiao capsules.