Ultrasonication was employed to prepare solid lipid nanoparticles (SLN). The model traditional Chinese medicine, tetrandrine (TET), was incorporated into SLN. The TET–loaded SLN (TET–SLN) were spherical in the photograph of transmission electron microscope (TEM). The particle size measured by laser diffraction (LD) was found to be 157.3±8.2nm. Zeta potential analyzer suggested the zeta potential of TET–SLN was −29.36±3.68mV in distilled water. The entrapment efficiency (EE%) was determined with the sephadex gel chromatogram and high-performance liquid chromatogram (HPLC), and up to 90.59% of TET was incorporated. Stability evaluation showed relatively long-term stability with only slight particle growth (P>0.05) after storage at room temperature for 4 weeks. Therefore, ultrasonication is demonstrated to be a simple, available and effective method to prepare high quality SLN loaded traditional Chinese medicine.