In order to study the test errors of cable tension due to natural frequency order and support condition, based on dynamical equilibrium of infinitesimal element, the formulas of natural frequency and cable tension were deduced under flexural rigidity. In terms of Ray-Leiy energy method, the influence of additional mass and elastic constrain on natural frequency was studied. The influence rule of test error due to test frequency order has the character of two times parabola. The natural frequency can decrease when added additional mass, and the influence of sensors mass may be neglected during ...