The invention discloses a novel boiling and bleaching process for pure flax yarn, comprising the following steps: (1), roving, (2), pre-bleaching, (3), spun yarn, (4), final bleaching: the bobbin The yarn is set on the creel, put into the bleaching pot, and carried out in the following order: a, pickling; b, neutralization; c, initial bleaching; d, rebleaching; e, washing. The invention ensures that the final bleaching of the spun yarn is not only more uniform, but also strong, the yarn quality is good, the broken end rate is greatly reduced, and the obtained flax spun yarn has gaps between fibers, and the handle is softer. The present invention divides the problems in the traditional scouring and bleaching and spinning processes into roving pre-bleaching and spun yarn final bleaching, and divides the difficult problem of traditional roving scouring and bleaching into two steps, which realizes the controllability of the process and ensures the hemp fiber spun yarn Higher yarn quality.