The invention discloses a flexible electromagnetic shielding material, a preparation method and application thereof. The flexible electromagnetic shielding material is prepared from flexible carbon fiber under an oxygen-free atmosphere through high-temperature treatment, wherein the high temperature ranges from 1200 DEG C to 1600 DEG C. The flexible carbon fiber serves as the raw materials, the argon atmosphere heat treatment is carried out at 1200-1600 DEG C in a tubular furnace so as to regulate and control the carbon ordering degree, the electromagnetic shielding performance of activated carbon fiber felt in the frequency range of 8.2-12.4 GHz is optimized, and the shielding performance of the activated carbon fiber felt reaches 32-38 dB after heat treatment and is increased by about 110% compared with original active carbon fiber felt. The method in use is simple and effective, and can be used for preparing special electromagnetic shielding function materials which are flexible, light and resistant to high temperature.