Abstract: A 20 L-Sphere, as one of the typical measurement set-ups, was used to measure and test the parameters of dust explosion characteristics. In respect to both the characteristic parameters and the violence of dust explosion, the RMS turbulent velocity plays an important role. So, a Laser-Doppler anemometer was applied to the measurement and testing of the velocity of dust particles in a 20 L-Sphere, with all the resulting data processed and discussed. The time-dependent curves of RMS turbulent velocity of dust particles at different positions were therefore obtained, thus providing data for the comparison between minimum ignition energies at different apparatus and also providing a basis for the verification of mathematical models of dust explosion. Such RMS values will benefit applying the data measured to industrial uses.