Brake theory of CNC table friction discs was analyzed.Formulas of friction discs elastic coefficient and brake torque were derived by using deflection model of cantilever beam under point load and were applied in an instance calculation.Finite element method (FEM) was used to verify friction discs elastic coefficient and calculate the torsion rigidity of the table.Test of table brake torque was designed,and the relationships between torque and deformation of the table under permitted load and overload load were obtained respectively.The calculation results of brake torque and torque rigidity of the table were verified.The research results provide basis for the design of the brake structure of CNC table and the whole machine tool debugging.