The length of a single fiber of hemp is 18mm or so, which is somewhat lower than that of flax. So it is possible to make the spun yarn with hemp. For the sake of high 7%~8% content of lignin in row fiber, even worse, it can not drop under the degree of 0.8% when treated by classical boiling off. That’s why the coarse stiff hemp fiber can not ever answer the demand of its spun yarn processing. The so called non-acid re-double-boiling out process developed on the renovation to the classic chemical boiling off of raw hemp can prevent the lignin from further fasculation under the inorganic acid preparation. At the same time, the OH— boiling off agent and HS— boiling off agent can cause a rapid thorough hydrolization of lignin, this undoubtedly will ensure the being of high quality refined dry hemp.