Context: Solanum nigrum Linn. (Solanaceae), a traditional Chinese medicine (TCM), has been used for cancer therapy. It is urgent to develop a novel quality standard to validly detect its quality. Objective: To control its quality, a novel, accurate, and valid fingerprint method was developed by high-performance liquid chromatography--evaporative light scattering detection (HPLC-ELSD) in the current case. We could evaluate the quality of different batches and assure the stability of herbs'' quality in subsequent research. Materials and methods: The HPLC-ELSD fingerprints have been developed through analyzing 41 batches of raw herbs collected from different areas in different harvesting time. Results: We have determined the optimum extraction and detection conditions in the process of establishing herb fingerprint. And, we could establish reference fingerprint to control such herb quality. Also, we could determine optimum collecting location and harvesting time according to the fingerprint. Discussion and conclusion: It is the first time a new method has been established to control the quality of S. nigrum through HPLC-ELSD. We developed combining similarity evaluation to identify and distinguish raw materials efficiently from different sources. For S. nigrum the most influenced factor on herb quality was the collecting location, and the next was the harvesting time. So, in order to get the consistent raw materials, the collecting location and the harvesting time should be fixed. [ABSTRACT FROM AUTHOR]