The objective of this paper is to obtain the developing tendency of outcrop coal fire under the multi-ventilation powers and fire pressure, so as to provide technical support for the governance of the fire area and ensuring mine work safety. The structural characteristic of the thermal dynamic system of outcrop coal fire under the control of multi-ventilation power factors have been analyzed and the practical application has been carried out. The thermal dynamic system of the outcrop coal fire under the control of multi-ventilation power factors include five sub-systems, namely combustion, heat dissipation of coal and rock, gas seepage and oxygen supply, gas discharge, and goaf leakage. Then, the mathematical model of the thermal dynamic system is set up and is applied in the old Shaft II fire area of Didao coalmine. At last, the changes of combustion product concentration, pressure and seepage velocity in the outcrop, which is under the condition of the even air pressure fan of the old Shaft II is done or stop, are acquired. As the even air pressure fan of the old Shaft II stops working, the seepage range in the fire area will reduce, and then, the growth speed in the fire area will reduce to some extent. However, because the pumping action of the even air pressure fan disappears, part of the combustion product will flow into working area of the coalmine. Thus, it is recommended to add automatic air door and CO sensor between the old shaft II and shaft XI in -480m main haulageway, so as to monitor the impact of fire area on work safety, and gradually close the fire area.