Diatomite particles with size distribution of 200-300 μm were used as emulsifying matrix carrier to prepare low detonation velocity emulsified explosive. The microscopic properties of diatomite were characterized. The effects of diatomite mass fraction on the particle size and detonation mechanism of explosive were analyzed. The density， detonation velocity and air explosion shock wave pressure of explosive were measured. The compatibility of diatomite and emulsified matrix was tested. The results show that when the mass fraction of diatomite increases from 15% to 35%， the particle size of explosive is negatively correlated with the content of diatomite， the density of explosive decreases from 0.79 g·cm^-3 to 0.51 g·cm^-3， and the detonation velocity decreases from 2561 m·s^-1 to 1655 m·s^-1. The peak pressure of air explosion shock wave decreases from 0.061 MPa to 0.023 MPa. The addition of diatomite has no effect on the thermal stability of emulsified matrix， and the diatomite and emulsified matrix do not react with each other under room temperature or heating conditions. The detonation velocity and the peak pressure of air explosion shock wave of the explosive stored for 2 days and 120 days drop less than 5%， indicating that diatomite has good compatibility with emulsified matrix.