Abstract: OBJECTIVE To prepare oleanolic acid-nano calcium carbonates solid dispersion and to enhance its in vitro release. METHODS Oleanolic acid-nano calcium carbonate solid dispersion was prepared by using solvent evaporation method. By using scanning electron microscopy (SEM)， differential scanning calorimetry (DSC) and X-ray powder diffraction (X-RD)， the Microscopic structure and physicochemical properties of solid dispersion were analyzed. And its in vitro release also was investigated. RESULTS It was suggested that oleanolic acid may be present in solid dispersion as amorphous substance. The in vitro release determination results of oleanolic acid -nano calcium carbonate (1∶2) solid dispersion showed accumulated dissolution rate of oleanolic acid was up to 83.30% at 60 min which was much higher than oleanolic acid bulk drug. CONCLUSION The results indicated that in vitro dissolution of oleanolic acid was improved greatly by the solid dispersion with nano calcium carbonate as a carrier.