More and more attention has been paid to the micromixer as its unique mixed features. In recent years, the micromixer has been applied to the preparation of the emulsion matrix. Two kinds of micromixers were used to complete separately the first emulsification and the second emulsification of emulsion matrix. Both of the emulsion principle of the split-recombine micromixer for high viscosity fluid and the influence of the width, length of the microchannel and fluid flow velocity on the emulsification effect were discussed. Results show that different types of micromixers are suitable for different stages of the emulsification. Under the conditions of the total fluid flow of 40 mL·min^-1, a good quality emulsion matrix with viscosity of 38000 cP and average granularity of aqueous phase of 1.895 μm is prepared by the micromixers. The dissolution loss rate of ammonium nitrate (AN) was 0.2497% after 30 days storage at room temperature. The emulsification principle of the caterpillar split-recombine micromixer for high viscosity fluids is the shear effect of the microchannel to the fluids. The width of the microchannel affects the pressure of emulsification significantly. The longer the length of microchannel is, the larger the flow velocity of fluid is and the better the quality of emulsification is.