Abstract: Comprehensive Performance of drilling derrick is evaluated by identifying the modal parameters and modifying the dynamic model.Based on structure characteristics and exciting vibration form of drilling derrick,the identification formula of modal parameters is derived and the revised first order search method of modifying the dynamic finite element model is introduced.The field dynamics test is carried out under transient brake excitation,and the first three natural frequencies and the first two vibration modes are identified.The practical running situations of drilling derrick are analyzed.The finite element model is modified with the revised first order search method based on the first two natural frequencies.The modified model can achieve the accurate inversion of the first three natural frequencies and dynamics characteristic,and it can also be used to take further analysis on the static and dynamic behaviors and the comprehensive performance.The new method to evaluate the safe and steady running of the drilling rig during operations is provided.