The invention discloses an orlon/viscose/chinlon/spandex polycomponent seamless underwear dyeing process, which belongs to the technical field of pretreatment, dyeing and afterfinish processes of knitgoods. The process comprises the following steps: dyeing viscose according to the prior dyeing viscose technological requirements; adding dyes and auxiliary agents to perform one-bath refining oil removal and dyeing orlon/chinlon/spandex; and finally performing softening treatment according to the prior softening treatment technological requirements, wherein the dyes and the auxiliary agents consist of an oil removing agent, a refining agent, an ED type cationic dye, a weak acidic or neutral dye, a precipitate preventing agent, a chelating dispersant, a leveling agent, glacial acetic acid, sodium acetate and the like. The process reasonably selects the ED type cationic dye, adds the precipitate preventing agent, performs the refining oil removal and dyeing orlon/chinlon/spandex in one bath, changes a four-bath process in the prior art into a two-bath process for dyeing, shortens the process flow and the dyeing time, improves the yield, reduces the using amount of steam and water, and reduces pollution discharge.