The invention belongs to the technical field of heat-insulating materials and particularly relates to a basalt fiber-based heat-insulating layer for nuclear radiation protection; a basalt fiber felt is used as a base, and flexible lead-fiber cloth is fixedly connected to the surface of the basalt fiber felt base and is fixedly connected to the surface of the basalt fiber felt base by means of sewing or bonding. Compared with the prior art, the basalt fiber-based heat-insulating layer has the advantages that impregnating emulsion is proportioned correspondingly and subjected to double impregnation, an infrared oven is used to perform primary treatment after primary impregnation to obtain the basalt fiber felt that has the features such as small heat conductivity coefficient, low heat capacity, low density, small linear expansion coefficient, good tolerance to high temperature, good impact resistance, and high resistance to chemical corrosion, and the basalt fiber-based heat-insulating layer has certain radiation shielding function, may be used in severe environment, is highly processable and may be used in the processing of containers of corresponding specifications as required.