To determine the optimum process for preparing Cinnamomi Cortex oil microspheres based on porous silicon dioxide. After porous silica dioxide adsorbed Cinnamomi Cortex oil, Cinnamomi Cortex oil microspheres were prepared by the dropping method, with sodium alginate as the skeleton materials. The preparation process was optimized through the L(9) (3(4)) orthogonal test design, with microspheres diameter, distribution, drug loading capacity and entrapment efficiency as the indexes. The cinnamon volatile oil microspheres were characterized by scanning election microscope (SEM), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. An in vitro drug release experiment was conducted. The results showed that the microspheres prepared with the optimal process parameters were in good shape, even in size and good in dispersibility, with an average diameter of 1.61 mm, an average drug loading capacity of 32.85%, an entrapment efficiency of 94.79%. The maximum drug release capacity reached 72.6%, 95.0%, 97.4%, respectively, under pH 4.0, 6.8, 7.4 in 6 hours. Meanwhile, microsphere generation was tested by IR, TGA and other methods. The established optimum process for preparing Cinnamomi Cortex oil microspheres was proved to be stable and practical.