A railway tunnel under construction in mountainous areas with complex geological conditions is confronted with the problem of no transportation channel for the secondary transfer of discarded slag. The technology of transfering slag with long and large chute is proposed and its key points are studied by field test and numerical calculation. The results show that: (1) The sliding velocity of slag particles increases with particle size, and the average friction coefficient is 0.16 when slag particles sliding in the chute. (2) The force of single fishbone baffle, the resultant force of fishbone baffle before and after 24 m, and the velocity of stone slag particles gradually increase with increasing fishbone baffle spacing, baffle angle, and the angle of folded energy dissipation structure,  while decrease with the increase of width of fishbone baffle and length of energy dissipation structure.