In order to ensure the safety of field mixed emulsion explosive， dynamic extrusion was used to simulate the charging process of explosive. The stability of field mixed emulsion explosive prepared at different rotating speed was studied by laser particle sizer， microscope， water-soluble ammonium nitrate precipitation test and digital viscometer. The experimental results show that crystallization instability in the emulsion matrix will occur in some extent under dynamic extrusion when the particle size is larger than 5 μm.After 10 times of dynamic extrusion， the amount of ammonium nitrate released from the emulsion matrix is 5.14 times of that before extrusion， the viscosity increases by 43%， and the W/O structure has been completely destroyed.When the particle size is smaller than 5 μm， the dynamic extrusion resistance of emulsion matrix is improved，after 10 times of dynamic extrusion， the particle size of emulsion matrix increased by 2.16 times， the amount of ammonium nitrate released from the emulsion matrix is only 2.14 times of that before compression， the viscosity increased by 10%， and the microstructure remained stable.The dynamic extrusion process will accelerate the crystallization instability of matrix， change the physicochemical properties， reduce the performance of emulsion explosive， and is not conducive to the loading process. In production practice， it is necessary to reasonably control the particle size D≤5 μm.