In order to explore the influence of cable damage on the dynamic characteristic of asymmetric single tower cable-stayed bridge，a prestressed concrete single tower cable-stayed bridge is taken as the engineering background，and the finite element analysis model is established. By reducing the elastic modulus of the cable，ANSYS life and death element command，the uniform damage and local cable fracture damage of the whole bridge are simulated respectively，and the dynamic characteristic of the damaged bridge are analyzed. The results show that there is an obvious linear relationship between the change rate of bridge natural frequency and the uniform damage degree of cables. The influence of cable damage in main span area on bridge natural frequency is generally greater than that in side span area. Long cable damage has maximum influence on the transverse bending frequency of first-order tower，and medium long cable damage has great influence on the vertical bending frequency of first-order beam.