The emergency braking of large wind power brake involves the multiphysical field coupling of friction,fluid,thermal elasticity,high energy density friction pairs,in order to further reveal its friction heat transfer principle,based on the theory of heat transfer the analysis,the thermalmechanical coupling threedimensional finite element mathematical model of wind power highspeed shaft brake was deduced.The transient thermal stress characteristics of the wind power brake were studied by the transient complete thermodynamic coupling method of finite element analysis software Abaqua.The results show that the uneven contact of the wind power brake dual parts causes the timeliness and asymmetry characteristics of temperature in the circumferential direction of plate.The law of temperature rise and stress change in radial direction caused by the alternation of heat transfer and heat flow input was explained,and the thermal crack initiation and propagation in the thermal stress concentration area was reasoned.It can be used as a reference for the study of high heat friction mechanism of high speed shaft brake disc of large wind turbine.