Abstract: For the property and application of dye random laser, the relations among the random laser emission threshold, luminescent properties, number density change and particle size of fluorescence particles and additional scattering particles in disorder media were discussed. Using the finite difference time domain (FDTD) method to solve Maxwells equations and rate equations directly, the curves of number density and emission line changing with laser emission threshold were simulated. When the mass fraction of Rh6G-SiO2 was 4% and the threshold was 8.5 J/pulse, the influence of additional TiO2 particles on random lasing was small enough to be neglected. Furthermore, we also simulated the threshold characteristics of random lasing in variety of conditions and background media.