The invention discloses a dyeing and finishing method of flax staple fiber. The method uses flax staple fiber as raw material, and undergoes pretreatment-scouring, one-bath pretreatment, hot water washing, warm water washing, dehydration, dyeing, cold water washing, and soaping , Washed in cold water, dehydrated and dried. The advantage is that the pretreatment process and the scouring pretreatment process are combined into one bath treatment, the process flow is shortened, and the pretreatment uses green peracetic acid instead of traditional sulfuric acid, which reduces the damage to fiber strength. This method can well remove impurities such as lignin, pectin, and pigment, increase softness and extensibility, reduce short-lint rate, significantly improve the splitting degree and spinnability of short fibers, and improve their quality and function. After adding the rubbing fastness improving agent, the dry and wet rubbing fastness is improved by 1~2 grades, and the comprehensive performance is improved. The produced combed short hemp high-count yarn has the same long-term physical index and yarn appearance quality as the linear density. Comparable.