The invention relates to a middle-voltage power transmission fire-resistant cable, which is characterized in that a fire-resistant layer out of a middle-voltage cable core includes an inner fire-resistant inorganic fiber thermal insulating layer, and an outer composite fire-resistant thermal insulating layer, which is a soft thermosetting elastic body in normal use and is a fire-resistant thermalinsulating layer when exposed to fire, wherein the thermosetting elastic body consists of 30-50wt percent silicon-based elastic material, 40-60wt percent inorganic filling material, 5-15wt percent middle- and low-temperature frit, and 4-10wt percent vulcanizing agent and is prepared by mixing, extruding, shaping and vulcanizing. The composite fire-resistant thermal insulating layer is a soft protective material for ensuring the good bending property of the fire-resistant structure under normal condition, can change to tubular fire-resistant thermal insulating structure when exposed to fire orhigh temperature and can not be damaged for a certain time in fire environment so as to effectively prevent the flame or high temperature from damaging the inner insulating layer. When the outer flame temperature is 850DEG C, the surface temperature of the inner insulating layer is less than 180DEG C. The fire-resistant thermal insulating structure can be applied in common cable protection mannerand has very high production efficiency.