In order to meet the equipment work on the building, the natural frequency of a high-rise tower structure should be greater than a certain value.The basic principles of structure frequency adjustment are to reduce the top mass of the structure and improve the bottom stiffness of the system, through the analysis of the fundamental frequency calculation formula and structure deformation curve. Based on the spatial finite element theory, we obtained the frequency and mode shapes of the structure through modal analysis. We used the ambient excitation identification method to test the dynamic property of the radar tower, and used the modal parameter identification method to identify the first three order frequencies, mode shapes and damping ratio of the structure. Then, we introduced modal assurance criteria and a normalized mode difference criterionto analyze and compare the calculated mode and the measured data. The results provided a reliable basis for further accurate predictions of the tower structure dynamic response and frequency adjustment.