Due to the variable braking conditions of wind turbine brake,the composition of the third body on the friction pair surface is complex and the size of third body is different,and the friction and wear characteristics of the friction pair under the influence of the third body remain to be studied.Taking the friction pairs of wind power brake in service as the research object,the components and dimensions of the third body attached to the friction pair surface of wind power brake were detected.The results show that the main components of the third body attached to the friction pair surface of the wind power brake are iron and copper wear debris and sand particles,and their dimensions are all in the order of 100 microns.The pin-disc friction and wear tester was used to study the effect of the third body of above-mentioned components and dimensions on the friction and wear characteristics of the friction pair.The test results show that the third body produces a rolling friction reducing effect between the friction pairs at the initial stage of friction,which greatly reduces the friction coefficient.As the degree of wear intensifies,the friction coefficient rises sharply,and the severe wear stage of friction pair occurs in advance.Iron particles will aggravate the wear of friction pair and shorten its service life.Sand particles will lead to large fluctuation of friction torque during braking,and copper particles will lead to insufficient braking force.