In order to study the accuracy of frequency method applied to monitoring the cable force of single cable glass curtain wall, based on the cable force monitoring project of some single cable glass curtain wall, finite element software ANSYS was used to establish the vibration model of the single cable glass curtain wall under different boundary conditions, and the simulated frequencies were compared with the measured frequencies. The results showed that the boundary condition of the curtain wall cable is closer to the fixed ends, and the shorter cable is more obvious;the higher order frequencies (n=3~6) are more stable than the lower order frequencies (n=1~2). The frequency correction coefficient was obtained by comparision of the measured frequency with the simulated frequency(n=3~6), and the number was 0.968 calculated by string theory formula. A modifier formula was proposed, which was suitable for the cable of single cable glass curtain wall whose ratio of length to diameter was between 270~340. The modifier formula was verified by the bow type dynamometer method, and the relative error of the cable force was -5.4%, which showed that the calculation accuracy of the curtain wall cable force could be effectively improved by the modifier formula.