Abstract: Slenderizing of wool by stretching is a novel technique,in its commercial application,however,there exist some problems such as the slenderizing effect can not live up to the expectation and the property of the slenderized wool is unstable.Therefore,we develop a laboratorial stretching apparatus on which simulation of commercial production of continuous stretching slenderizing of the 64s local wool was carried out.Then the physical properties such as the fineness,length,strength and elongation of the slenderized wool were tested and compared with those of Optim~D○R.The results showed that the average fineness of the slenderized wool fibers decreased by 16.1%,the length increased by 26.4%,and the tenacity of fiber increased by 23.49%.This demonstrates that this stretching slenderizing process is satisfactory.In addition,the elongation rate at break of the slenderized wool is lowered remarkably,and its elasticity is also decreased.