In order to calculate the bearing capacity and residual fatigue life of JJ113/32 derrick structure in service, static and dynamic load tests were carried out on the derrick in the field. The finite element simulation model was established based on I-DEAS software; under the test hook load, the results of the two models were in good agreement, and the accuracy of the model was verified. According to the comprehensive analysis,the weak member of the derrick is located at the bottom of the No1 vertical column, and the maximum stress is less than the limit stress of the material, which meets the requirement of the original maximum design hook load.The calculation results of the fatigue life of the derrick members show that the derrick has a greater life safety factor andcan be used continuously during the service period.