The thermal ageing properties of lubricating greases were simulated under limited operating temperature of 150 ℃ and by using static thermal ageing method.The effect of aged time on fibrous entanglement,shear property and reversibility of lubricating greases was carried out by using rheological method.It is found that the fibrous entanglement of aged grease samples is decreased with the increasing of aged time at first and then increased,and the variation of apparent viscosity under continues shear condition displays the similar tendency.Compared with the new grease samples,the lubricating grease samples after being aged are hardened and the reversibility is gradually decreased as well.