Objective To develop the formulation of self-microemulsifying drug delivery system for hawthorn leaves flavonoids (HAW-SMEDDS). Methods The optimum formulations of oil phase, surfactant, and assistant surfactant for HAW-SMEDDS were screened by solubility test, compatibility test, and pseudo-ternary phase diagrams, with the time of formulating microemulsion, the consequence of visual examination, and particle size as indexes. The dissolution of HAW-SMEDDS was measured, taking the commercial tablet Yixintong Tablet as reference. Results The optimum self-microemulsifying drug delivery system was composed of Labrasol (35%), Transcutol P (10%). The particle diameter was (39.5?5.4) nm, the time of self-microemulsifying was less than 1 min. The percent of accumulated dissolution of hawthorn leaves flavonoids in SMEDDS in distilled water was up to 70% at 10 min, while that in the Yixintong Tablet was less than 50% at 60 min. Conclusion The formulation of HAW-SMEDDS preparation could meet the request of the design. It could provide the reference for the new dosage form.