As the problem of fastener screw bolt fracture and affect the operation safety in some subway lines, field experiments were carried out to obtain the relationship between the torque and axial force of screw. Based on the measured data and considering the irregular spatial shape of spring washer, non-uniformity of the contact stress, and nonlinear contact between different parts, etc, fine finite element model of fastener screw was established. The mechanical characteristics of each component of the screw with single and double spring washers were analyzed respectively. The results show that compared with the single washer, the axial force of screw with double washers increases less under train load and the possibility of damage is greatly reduced because of the shear deformation in the compression state. The special shape of spring washer causes stress concentration in the combining site of nut and washer, partial load on nut, it is an important reason that the crack are easy to be generated and expanded in the combining site of nut and washer. These analysis results coincide with the actual situation.