For energy conversion with high efficiency and low carbon emission, Oxy-Coal Combustion Steam System for power generation with near-zero emissions was proposed. The Ignition Temperature of Yimin demineralized coal and Zhundong demineralized coal were studied in a one-dimensional drop tube furnace at different oxygen concentration and steam concentration. The impact of pressure on the ignition temperature was investigated by High Pressure Steam TGA. The results show that the oxygen volume concentration is very important for the ignition temperature of demineralized coal. With the increasing of oxygen concentration, the ignition temperature is gradually reduced. With the increasing of the concentration of steam, the ignition temperature is gradually raised. When the steam volume concentration, range from 10% to 50%, increases 10%, the ignition temperature increases about 30 ℃. When the pressure is less than 1.0 MPa, with the increasing of pressure, the ignition temperature of Zhundong demineralized coal decreases, when the pressure is in the range of 1.0-2.0 MPa, then no obvious change for the ignition temperature, but when the pressure is greater than 2.0 MPa, the ignition temperature increases.