Abstract: In order to study the relation of the rock dust content and moisture content in coal-rock roadway with the minimum ignition temperature of the mixed coal-rock dust cloud, five kinds of coal samples with different volatile matter were selected for separately preparing the mixed dust with different rock and moisture content, and the test device of dust cloud minimum ignition temperature and the control variable method were used to measure the minimum ignition temperature of the mixed coal-rock dust cloud. Test results showed that rock dust not only had the effect of suppressing explosion, sometimes would also promote the dust explosion. The increase of moisture content may cause the rise of the minimum ignition temperature of mixed dust cloud, when the mass fraction of water was higher than 20%, the increase of the moisture content may greatly increase the minimum ignition temperature of the mixed dust cloud; the less the volatile matter of the mixed dust, the more sensitive of the mixed rock to the change of rock dust content and moisture content. In the prcess of the production and drivage of the coal-rock roadway, water spraying should be taken for increasing the moisture content of the mixed dust so as to prevent the dust explosion.