There are quality issues such as the stochastic volatility of tightening performance and the decline of the tighten quality stability in the operating process in tightening equipment. For the quantitative characterization of the degree of performance stochastic volatility and disorderly state, information entropy and Lempel-Ziv algorithm complexity of both indexes are applied respectively in this approach to characterize the performance. First, the tightening performance indicators are divided into several states, and the mathematical model of the tightening performance complexity is established based on information entropy theory in order to quantify the random fluctuations extent of tightening performance. Meanwhile, the performance complexity of tightening equipment is also measured based on the Lempel-Ziv algorithm, which gives an approach to describing the disorder of the performance. Finally, the proposed approach is used in an example and the torque and angle data are comparatively analyzed to verify the validity of the proposed approach in the example. The results show that the torque and angle indicators consistently reflect similar trends in equipment degradation. The evaluation results of the information entropy and Lempel-Ziv algorithm describe some differences in the operation process. The performance degradation of the tightening equipment is measured from two dimensions of stochastic volatility and disorderly state.