The invention relates to a method for detecting a pharmaceutical preparation, in particular to a method for constructing a fingerprint chromatogram of a traditional Chinese medicine preparation, namely, a radix codcnopsitis pilosulas, ramulus cinnamomi and poria cocos oral solution. High performance liquid chromatography is mainly adopted for detection, an acetonitrile-0.5% glacial acetic acid aqueous solution is taken as a mobile phase, A is acetonitrile, a 0.5% glacial acetic acid aqueous solution is taken as a mobile phase B, the detection wavelength is 203 nm, the column temperature is 30DEG C, the injection quantity is 10 mu l, and all the components are detected within 60 min.