The invention relates to the field of design and preparation of nuclear radiation protection materials, in particular to a flexible radiation protection material with functions of radiation warning and temperature adjustment and a preparation method of the flexible radiation protection material. The flexible radiation protection material is used for manufacturing radiation protection garments and is in a three-layer structure comprising a radiation warning layer, a radiation shielding layer and a temperature adjusting layer. The preparation method of the protection material which is processed layer by layer includes: firstly, forming the temperature adjusting layer, namely mixing and spraying room-temperature vulcanized silicon rubber and a phase-variable energy storage capsule material to release cloth, and blowing hot air for curing; secondly, mixing and spraying the room-temperature vulcanized silicon rubber and filler with a shielding function to the temperature adjusting layer, and blowing hot air for curing; finally, mixing and spraying the room-temperature vulcanized silicon rubber and a fluorescent powder material to the radiation shielding layer, and blowing hot air for curing. The flexible radiation protection material is excellent in flexibility and gamma-ray/X-ray shielding performance and has the functions of radiation warning and temperature adjustment, thereby being an excellent core material for novel radiation protection garments.