The servo turret is a key component of the CNC lathe, and it is the most vulnerable component of a CNC lathe. We can find the weakness of the product by reliability test and improving the reliability. The load spectrum is a prerequisite for carrying out the reliability test. However, there are many small loads in the current load spectrum. These small loads have little influence on reliability. To shorten the test time and improve the test efficiency, the spectrum is recompiled to compress the load spectrum. In this paper, the cutting force is extrapolated in the time domain after processing. Then, the mean and magnitude of the load are counted by the rain flow counting method, and an eight-level load spectrum is compiled. At the same time, the finite element model of the servo turret was established, and experiments verified the model. The eight-level load spectrum is input into the established finite element model and the servo turret reliability test system, and the stress information and vibration information are obtained respectively. The load is classified by means of information entropy, and the compressive load spectrum is obtained by ignoring the light load.