The invention relates to a multifunctional thermal underwear fabric and a processing method thereof, belonging to the field of textile technology. The multifunctional thermal underwear fabric comprises a face weave and a bottom weave, wherein the face weave consists of cotton fibers, polyester fibers, spandex fibers, bamboo charcoal fibers, viscose fibers, wool fibers and plant protein fibers; and the bottom weave consists of polyester fibers. The content of the cotton fibers accounts for 34-60 percent of the total components, the content of the polyester fibers accounts for 26-39 percent of the total components, the content of the spandex fibers accounts for 5-6 percent of the total components, the content of the bamboo charcoal fibers accounts for 0.5-6 percent of the total components, the content of the viscose fibers accounts for 1-17 percent of the total components, the content of the wool fibers accounts for 1-5 percent of the total components, and the content of the plant protein fibers accounts for 0.5-7 percent of the total components. The multifunctional thermal underwear fabric has the advantages that the functions of the fabric are expanded by guaranteeing an excellent warmth keeping performance through the cotton fibers, by guaranteeing ideal elasticity through the spandex fibers, by reflecting a good moisture absorbing performance and air permeability through the polyester fibers and by reflecting a good antibiotic property through the bamboo charcoal fibers; and since function processing, baking and secondary ironing processes are increased, the fabric has an aromatic long-lasting effect.