Abstract: To analyze the vibration characteristics of the irregular arm frame itself,after reasonable simplification for the three-dimensional model of the irregular arm frame,modal analysis of the irregular boom is carried out by using the finite element analysis software ANSYS Workbench. On the basis of obtaining the fixed frequency and related vibration modes of the components, harmonic response analysis of irregular arm frames is conducted to analyze the response of the irregular arm frame under excitation load within a certain range. The research results indicate that the minimum natural frequency of the irregular arm frame is 371.12 Hz except for the rigid body mode, and the first six modes are basically arm swinging up and down,swing left and right and torsional equivalent vibration mode.Therefore, in actual operation, it is necessary to avoid working under loads within the range of 371.12 to 956.75 Hz and nearby loads. It provides a basis for predicting and optimizing the overall performance of the machine.