The invention relates to a sealing clearance self-adjusting steam sealing device having a gas suspension effect. The sealing clearance self-adjusting steam sealing device comprises a plurality of steam sealing arc sections, auxiliary sealing strips and springs arranged among the steam sealing arc sections; steam sealing teeth are arranged on the steam sealing arc sections; the steam sealing teeth are matched witha rotor surface to form sealing clearances, and the clearances of the steam sealing teeth at a high pressure side are larger than the clearances of the steam sealing teeth at a low pressure side; a high pressure steam introducing trough and a low pressure steam introducing trough are separatelyarranged in the middle positions of the steam sealing arc sections, cavities at the back of the steam sealing arc sections communicate with the high pressure side and the low pressure side, and high pressure steam and low pressure steam are obstructed by the auxiliary sealing strips. According to the sealing clearance self-adjusting steam sealing device having a gas suspension effect, sealing clearance self-adjusting steam sealing with a gas suspension effect is adopted, thus achieving automatic change of the sealing clearances according to two states of start and stop and normal operation of a steam turbine, being capable of automatically adjusting the sealing clearances in real time according to the position of the rotor, ensuring that the sealing clearances in an operation state are kept in a design scope all the time, keeping good sealing performance for a long time, having a function of reducing shafting vibration amplitude at the same time and comprehensively improving the operation safety and economical efficiency of the steam turbine.