Abstract: For many years, some accidents of derrick collapse have happened occasionally, so to forecast the actual bearing capacity of derrick structure reasonably, which has become the important content of the rig derrick safe evaluation research. This paper first analyzed the relationship between the dynamic parameter of derrick structure and the load acting on it by vibration theory, and to confirm it through the laboratory derrick model dynamic test. On this basis, the dynamic parameter evaluation method of the derrick safety bearing capacity had been proposed. And this method was used to the laboratory derrick model. In order to guarantee the reliability of the evaluation result, the method to evaluate derrick safety bearing capacity was proposed by testing the natural frequencies of the derrick under two different loads acting on it, the load is more than 10% of the security hook load in practical application. This method has promulgated the relationship between derrick bearing capacity and the natural frequency of it, and inaugurated the new way to test and evaluate petroleum derrick.