The invention provides a double-trench flat-bottom mining method for ores difficult to mine. The method includes the process steps that firstly, based on a sublevel caving method without sill pillars, three inlet channels are classified into one stoping unit, a transverse ore outlet channel is made from the middle inlet channel to the inlet channels on the two sides, and a bottom structure for double-trench ore falling and flat-bottom ore discharging is formed; secondly, in the stoping process, just like the inlet channels conducted through the sublevel caving method without sill pillars, for the trenches in the two sides, row-by-row blast hole blasting is conducted for mining retract, the ores do not stop being discharged until a driver of a scooptram does not enter an open stope and the ores cannot be discharged, and the caved ores which fall into the open stope and the ores which fall after roof hanging are discharged through the transverse ore outlet channel; thirdly, stoping is conducted at the two trenches at the same time, and the continuous mined-out area span is formed and exceeds the critical falling span of the hanging roof ores and roof surrounding rock, so that the roof surrounding rock falls naturally along with falling of the ores, and a covering layer is formed; and fourthly, the ores stop being discharged after the ores discharged from the transverse ore outlet channel reach the cutoff grade, an ore outlet roadway is formed through row-by-row caving in an inlet channel mining retract manner according to the sublevel caving method without sill pillars, and ridge residual bodies are recovered.