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ABSTRACTHeavy K-type derrick is one of the most important load-carrying parts in deep well oil drilling rig. Field test is a useful way of obtaining the dynamic characteristic parameters of the derrick but inherent disadvantages such as high cost, site condition limit its application. It is economical and effective to make reduced-scale dynamic model and do experiments for improving design of the derrick prototype. Based on similarity principle, we develop a reduced-scale dynamic model of the derrick prototype with geometric similarity ratio of 10. Dynamic test for the model and harmonic-response analysis for the derrick prototype have been conducted, respectively. The result shows that the maximum deviation of frequency and displacement between test and analysis is small, which proves the rationality and validity of the design and manufacturing of the dynamic model. Also, the test and harmonic-response analysis data indicate that in drilling process, the rotation of the rotary table can hardly ever cause the severe vibration of the derrick. The experimental dynamic test of reduced-scale derrick model can replace the field test of the derrick prototype and provides reference for dynamic characteristic research of the derrick prototype.