Abstract: A lot of poisonous and harmful smoke flow with high temperature will be produced when there is a fire in coal mine underground. The smoke flow will move along mine roadway and have serious danger for underground personnel and devices. So the paper researched movement rule of fire smoke flow of inclined roadway and horizontal roadway: when fire happens in upstream ventilating roadway, fire smoke flow will move downstream of fire area because of functions of fire pressure and buoyancy effect; when fire happens in downstream ventilating roadway, fire pressure is smaller at early stage of fire, so fire smoke flow will move downward along direction of air flow of roadway; with increasing of fire, fire pressure increases constantly, fire smoke flow will move along direction of fresh air flow when air speed of upstream is lower than critical air speed; function of throttling effect is not obvious at early stage of fire in horizontal roadway, fire smoke flow will move along direction of fresh air flow; with increasing of fire, function of throttling effect increases, fire smoke flow will make reverse movement when value of throttling effect is as big as value of ventilating resistance of roadway. The paper has certain guilding function for relief work of fire of roadway.