Cashmere yarn may be damaged in skein dyeing, resulting significant reduction of yarn strength. The factors affecting yarn strength include the selection of dyestuff, auxiliaries, pH value, temperature, processing time, liquor ratio and so on. Moreover, the style of management and attitude of the technicians also contribute to the final result. The cashmere yarns from Erdos were used in this study to quantitatively investigate the factors affecting the strength of dyed yarns. The optimal dyeing conditions for the least damage were found to be pH value 3.5, dyeing temperature 80 °C, processing time 90min, bath ratio 1:30.