The invention relates to infrared camouflage fiber and a preparation method thereof. The infrared camouflage fiber is prepared with a polymer matrix material, low-infrared-emissivity powder and additives. The preparation method comprises the following steps: drying the polymer matrix material at a certain temperature, mixing and evenly stirring the dried polymer matrix material, the low-infrared-emissivity powder and the additives according to a proportion, melting, filtering and spinning the mixture through a screw extruder, cooling trickles for formation, stretching, heat-setting and cutting, thereby obtaining the infrared camouflage fiber. Since the low-emissivity powder and the matrix polymer are blended and melted to uniformly introduce the power into the fiber and obtain the infrared camouflage fiber with functional durability and comfortable wearability, the invention overcomes the defects of the prior art that the bonding fastness of the coating and fabric is poor, the coatingcan easily fall off, the wear resistance is low, the feeling is poor, the air permeability is low and the like. Simultaneously, due to the addition of the additives, the invention reduces the surfaceactivity of particles, so that the low-emissivity powder can be dispersed in the matrix polymer more uniformly.