In the transmission system,nylon 66 parts will cooperate with steel parts to transmit motion and torque,because the hardness of nylon 66 is much lower than steel,so the surface of nylon 66 parts is very easy to produce wear and tear leading to failure,so the friction and wear of nylon 66 must be considered in the product design.In order to effectively evaluate the friction and wear performance of nylon 66 and steel pair,the friction and wear test of nylon 66/45 steel pair under different loads was carried out,and the wear morphology and the depth of wear marks were observed by super depth of field.The grey GM (1,1) model of wear prediction was established by using the grey system theory,and the wear prediction model considering the surface contact stress was established.The results show that the prediction of wear of nylon 66/45〖JP〗 steel pair by using gray theory has high accuracy and reliability,and the maximum error between the predicted and tested values is 9.26%,and the average relative error is 3.60%.Using this prediction model to design the wear life of nylon parts,there is no need to carry out a large number of repeated wear tests,and it can quickly provide the wear parameter index for the product design of nylon parts