The invention relates to the field of clothes, and particularly discloses antibacterial thermal underwear and a production process thereof. The antibacterial thermal underwear comprises a surface layer, wherein the surface layer is formed by blending various fibers including antibacterial fibers, and the antibacterial fibers are nano-silver / chitosan / polylactic acid composite fibers; the preparation method of the antibacterial thermal underwear comprises the following steps of S1, spinning, namely, blending various fibers including the antibacterial fibers to prepare blended yarns; S2, weaving,namely, weaving the blended yarns by adopting a single-sided and double-sided alternate weaving mode to weave gray cloth; S3, napping, namely, napping the skin-friendly surface of the gray cloth to obtain napped gray cloth; S4, dyeing, namely, dyeing the napped gray cloth; and S5, sewing, namely, sewing the dyed napped gray cloth to prepare a finished product of the thermal underwear. The thermalunderwear prepared by the invention has good lasting antibacterial property.