Abstract: OBJECTIVE To confirm a novel tadalafil derivatives added illegally into the traditional Chinese medicines. METHODS The target compound was separated and purified by preparative liquid phase, characterized by high performance liquid chromatography, liquid chromatography-mass spectrometry, nuclear magnetic resonance hydrogen spectrometry and other means, and its structure was concluded based on the literature reported. RESULTS The new compound was identified as a novel derivatived tadalafil based on the data analysis and literature reported. CONCLUSION The compound has not been in the scope of current detection range of PDE5 inhibitor illegally added in traditional Chinese medicines, as a newly derivatived tadalafil. This work provides a basis for further improving the quality control of PDE5 inhibitors.