Abstract: Two kinds of anti-setting agents synthesized in the laboratory were used in cashmere fibers simulation dyeing process under different conditions.Their protective effects were evaluated in terms of length,diameter,elongation at break and breaking strength of both the treated and untreated fibers.Experiment results show that the two kinds of anti-setting agents have remarkable protective effect for cashmere fibers during dyeing process.The fibers dyed in presence of anti-setting agents were superior to those dyed in absence of the agents in terms of all properties.The hydrophobic agent with high active functional group is better than the one with low active group.The longer the dyeing time,the shorter the fiber length,the coarser diameter,and the worse the tensile properties.When the anti-setting agents used in the range of 3% ~8%(o.w.f) during dyeing,it is beneficial to reducing the damage of cashmere fibers with increase of dosage.