Abstract: It will highly reduce the transport work of truck at working area and internal dumping area when adopts the single bridge at bottom of large surface mine.It can also reduce the freight and save the mine production costs.In order to determine the application scope of bridge，fractions model at working face was established to determine the scale of overburden and location of bridge surface.The transport work model before and after bridging during internal dumping and the optimization of inequality were built to determine the shortest distance of working line at the level of bridge surface and service height of bench.Haerwusu surface coal mine is taken for instance to verify the correctness of the model.The results show that the bridge is located at the lower or medium part，and the overburden at bridge surface is classified into four levels.The distance of interval dumping is most saving.The shortest distance of working line at the level of bridge surface is 1192.4 m and service height of bench is 60 m.The results play a guiding role in choosing bridging transport system of the mine with internal dumping.

Key words: Surface mine, Internal dumping, Single bridge, Transport work, Adaptability