The invention relates to a high temperature resistant nylon fiber for manufacturing wig and a preparation method thereof. The fiber is prepared from the following raw materials in parts by weight: 100parts of PA nylon slice, 1 to 10 parts of additive, 0.1 to 10 parts of pigment, and 0.1 to 5 parts of dispersed wax, wherein the additive is at least one of calcium carbonate, talcum powder, titaniumdioxide, silicon dioxide, diatomite, silica powder, glass bead and mica powder, and the temperature resistant range of the pigment is 180 to 350 DEG C. The preparation method comprises the followingsteps: step a, drying raw materials; step b, carrying out single screw extrusion; step c, cooling nascent fibers; step d, applying oil; and step e, carrying out thermal setting and packaging. The prepared fiber is very smooth and has excellent breathability, good moisture removing performance, and unique and natural luster, which is like the luster of real human hair. Moreover, the environment isnot polluted during the preparation process, and no wastewater or waste is generated.