Debris in lubricants affect the lubrication performance of lubricants directly,which causes the aggravated wear and extra vibration of the friction pairs,and puts a threat to lifespan and reliability of the equipment.To research the inductive relationship of debris to friction vibration,the friction vibration induced by debris in lubricants was studied on the fourball tester by changing the material,size and concentration of the debris.Experimental results show that,within a certain range,the smaller the hardness of debris is,the easier it is to induce the friction vibration.Smaller size of debris can induce friction vibration easily within the size range of debris used in the experiments.There is a critical value of debris concentration that can cause the biggest friction vibration,the friction vibration will decrease when the concentration of debris is less than the critical value,and the friction vibration will disappear when the concentration of debris is higher than the critical value.